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GNU Backgammon Manual V0.16

1. GNU Backgammon Manual V0 16 75 82 12 6 Analyzing 12 6 1 What are these funny letters at the right bottom You will find two small windows titled Position and Match ID at the bottom of the GNU Backgammon window Here you may use the position_id or match_id format for setting up or copying positions An explanation of both formats is found in the GNU Backgammon s documentation 12 6 2 How do I set up a position manually Open a new game match or session If gnubg already rolls the dice don t bother Press edit and either type the position_id and press Enter on your keyboard or use the mouse to set up the checkers A mouse click at the border of the board empties the point A left or right click sets up a certain amount of checkers depending on where exactly on the pip you click Set up the cube with a right mouse click on it You can also drag and drop checkers when holding down the Ctrl key Finally go to the menu and select Game Set turn to choose the player on roll The dice will then disappear 12 6 3 Which formats must I use to import matches and positions Import of matches and positions from a number of file formats is possible bkg Hans Berliner s BKG Format gam Gam monEmpire Game gam PartyGammon Game mat Jellyfish Match pos Jellyfish Position sgf Gnu Backgammon File sgg GamesGrid Save Game tmg TrueMoneyGames txt Snowie Text 12 6 4 How can s
2. 1 cubeful 1 truncate bearoffOS 1 seed 1177750272 quasi random dice 1 minimum games 144 date 13 7 2003 X rating 0 Exp 0 name Jon Royset event World Championship 2003 GNU Backgammon Manual V0 16 59 82 11 3 4 Python game A dictionary containing the following items info General game info For example gt m games 0 info points won 1 score X 0 score O 0 winner X resigned False If no winner is specified winner is None gt m games 2 info score X 2 winner None score O 0 game A Sequence of actions stats optional Game statistics Similar entries to Analyze Game statistics from the GUI 11 3 5 Game actions Each action is a dictionary 11 4 Guile scripting Earlier versions of GNU Backgammon had support for guile scripting which however was unused and un maintained and therefore removed 11 5 Equities explained 11 5 1 Introduction to equities GNU Backgammon works with many different kinds of equities The equity is defined as the expected value of the position However this value can be expressed in several different metrics and may be calculated with or without taking the effect of the cube into consideration In the following section we will describe the equities used and calculated by GNU Backgammon 11 5 2 Mone
3. 0 035 0 145 5 Cubeful 0 ply 24 22 24 20 Eq 0 006 0 185 6 Cubeful 0 ply 24 18 Eq 0 009 0 189 GNU Backgammon Manual V0 16 48 82 7 Cubeful 0 ply 24 20 6 4 Eq 0 019 0 199 8 Cubeful 0 ply 13 9 6 4 Eq 0 024 0 203 9 Cubeful 0 ply 13 7 Eq 0 052 0 232 10 Cubeful 0 ply 24 20 8 6 Eq 0 053 0 232 If we instead request a 4 ply checker play decision GNU Backgammon will use the move filters defined for 4 ply Ply Accept moves Extra moves Threshold for extra moves 0 0 8 0 160 1 no pruning 2 0 2 0 040 3 no pruning The 4 ply move filter is identical to the 2 ply for pruning at 0 ply so after 0 ply we have the same three moves as above Since there is no pruning at 1 ply these three moves are evaluated at 2 ply as above There is no pruning at 3 ply At 4 ply we do not accept any moves but add up to two moves if there within 0 040 from the best move Since the second best move is 0 138 worse than the best move we do not accept any moves to be evaluated at 4 ply Hence GNU Backgammon will actually not evaluate any moves on 4 ply The predefined move filters all have accept 0 moves in order to facilitate fast decisions and analysis 1 e no need to waste much time over obvious moves For post mortem analysis it may be worthwhile to ensure that GNU Backgammon analyzes at least two moves at the specified ply To do this specify accept 2 moves
4. 82 EB GNU Backgammon Analysis Settings QM Ry Analysis Chequer play Cube decisioms F Chequer play Predefined settings Predefined settings E Cube decisions Select a predefined setting Select a predefined setting Luck world class world class F Analyse player gnubg PIE STS settings User defined settings Lookahead Lookahead Plies 2 l Plies 2 F Analyse player user Move limit 20 a Skill thresholds Very good 1 00 Good 1 00 Doubtful 0 04 Bad 0 08 Very bad 0 16 Reduced evaluations No reduction Reduced evaluations No reduction Cubeful evaluations Cubeful evaluations F Cubeful chequer evaluation F Cubeful chequer evaluation B Noise 5 A Noise 0 000 O ACICICICICG Noise 0 000 rLuck thresholds Deterministic noise Very lucky 0 60 Deterministic noise Lucky 0 30 Unlucky 0 30 Move filter Normal Modify 310235363 Very unlucky 0 60 Cancel Figure 17 Analyze settings dialog In the top left frame in this dialog box you can select what to analyze GNU Backgammon is able to analyze three different properties in a match 1 Checker play 2 Cube decisions 3 Luck of each roll In addition you can have the analysis to analyze just one of the players or both There is also possible to set a limit of how many moves to be analyzed at each position When you re reviewing your match the number of analyzed moves will be limited to
5. D D gt 2 12 Game 1 gnubg o anth Z gnubg anthon 0 13 8 5 6 5 13 14 15 16 17 18 197207217722 023 24 1 22 24 22 2 6 4 2 36 24 15 2 63 13 10 4 13 bar 22 6 5 3 14 13 8 32 24 22 13 10 4 35 13 5 64 10 4 8 4 5 24 6 2 4 2 66 22 16 2 13 7 2 6 46 8 4 8 2 31 8 4 7 52 8 3 5 3 36 16 13 16 10 8 65 13 8 13 7 64 13 7 10 6 9 44 8 4 7 3 6 2 2 Double to 2 10 Drop Didn t double Rolled 36 0 047 Moved 24 15 Checker play Cube decision 1 Cubeful 2 ply 0 063 24 18 13 10 2 Cubeful2 ply 0 064 0 002 24 15 3 Cubeful 2 ply 0 153 0 090 13 4 ILLIA 4 Cubeful 2 ply 0 158 0 095 13 10 13 7 5 Cubeful 0 p 0 251 0 189 24 18 8 5 z gnubg 0 anthon Y Y Match unlimited l e Show Details Score 0 Score 0 aaa Pips 159 4 Pips 163 4 B iii GNU Backgammon is a world class opponent and rates at around 2000 on FIBS the First Internet Backgammon Server at its best it is in the top 5 of over 6000 rated players there GNU Backgammon can be played on numerous other on line backgammon servers The following features can be found in the current release of GNU Backgammon e A command line interface with full command editing features if GNU readline is available that lets you play matches and sessions against GNU Backgammon with a rough ASCII representation of the board on text terminals e Support fo
6. Game actions Introduction to equities o ooa a Money equity e a ee ER N 6 82 A E eRe God ET a 44 GNU Backgammon Manual V0 16 7 82 11 5 3 Match Winning Chance 264 st he eed ee EAs eRe Ee Ee ee ed ERE Sew e 59 TLS Normalized equity xpd oS ee Sy ei Sw Ee Ewer Ss ew ES Sede AA 4 60 1 5 5 Cubefulequities cimas o ee a bade Pee ea ea ee 60 11 5 5 1 Basic formula for cubeful equities 2 0 0 0 002 0000 60 11 332 Tavecub equities ies 4 ek iy BS AA Beets Yew ne eae se 61 11 5 5 3 O ply Cubefulequities s s pi N N T a ee 63 11 5 5 4 n ply Cubeful equities 2 oaa ee 63 11 5 5 5 The cube efficiency 2 66 25 4 2s be wae NR ew Ee a eae Se 64 11 53 6 Cube decisions s a s sk a R R R a GE Go eG Bang Ma eS a T ak 64 11 5 5 7 Beyond the simple model 2 2 2 0 2 00 0000 00 02 0000 65 11 6 A technical description of the Position ID 2 020 000 0000 00000000 0 00004 65 11 7 A technical description of the Match ID 2 2 0 0 000000000000 0000000 66 11 8 Description of the CSS style sheet 0 000000 0000000000000 0000 69 12 Frequently Asked Questions 70 12 1 eneral questions ic Sear e e A RR A A a eA RR ak de Se ale poe Ge N 70 12 1 1 Whatis GNU Backgammon 2 2 20 0 00000 a 70 12 1 2 What operating systems are supported 2 e 70 124 3 Where do L petit de 4 gid eM ee He oe Eee bt eM Se Sate ewe beets amp 4 70 12 1 4 What do I have to
7. same formula as Snowie 4 GNU Backgammon Manual V0 16 41 82 4 Overall rating Based on your normalized error rate per move GNU Backgammon will assign you a rating ranging from Awful to Supernatural See the table below for the thresholds 5 Actual result The actual result of the game or match For money game this is simply the number of points won or lost during the game or match For match play the number is calculated as 50 added to the result of the game or match in MWC For example losing a match or winning a match corresponds to an actual result of 0 and 100 respectively Winning point in the first game of 7 point match is worth 6 using Kit Woolsey s match equity table hence the actual result is 56 6 Luck adjusted result The luck adjusted result is calculated as the actual result plus the total unnormalized luck rate This is also called variance reduction of skill as described in Douglas Zare s excellent article Hedging Toward Skill This should give an unbiased measure of the strengths of the players 7 MWC against current opponent For match play GNU Backgammon will calculate your MWC against the current oppo nent The number is calculated as 50 your total unnormalized error rate your opponent s total unnormalized error rate If your opponent is really lucky but plays rather bad this number can become larger than 100 since he due to the extra luck has the possibly to give up even more MWC However GNU B
8. 14400 P3 1GHz PCG R600HFPD 256 MB Win XP SP2 0 16 mingw 13000 3 AMD 1GHz Jetway 1536 MB Win 2000 0 14 devel Intel Pentium M Sony Vaio Windows S aag 0 8 GHz PCG SRX51P MB XP SP2 nee 6200 eri Sad toshiba laptop 256 MB Win me 0 14 devel 1 These are the two versions evaluated on the same machine Big difference 2 According to cat proc cpuinfo 3 Highly variable 12000 13700 12 3 Running GNU Backgammon 12 3 1 I get an error message when starting Well your computer wants to communicate with you Give it a chance and read and try to understand what it is telling you Then read the next items carefully 12 3 2 GNU Backgammon complains about missing files GNU Backgammon reads several different files at start up It will first try to read a file called gnubg wd This is a file which contains all the neural net weights and is necessary for the program to evaluate positions If this file is not found or found corrupted or with an incompatible version GNU Backgammon will search for a weights file called gnubg weights This file also contains the neural net weights but is stored in ASCII format If none of these files are found GNU Backgammon will start but it will give you a warning about these missing files and it will play very poorly GNU Backgammon will also read the bearoff databases at start up There are usually two bearoff databases The first is called gnubg_os0 bd and has stored data about the bearoff probabil
9. In the case of a red line it is the move that was played 5 1 2 Getting cube decision hints while playing If you re thinking about a cube decision before rolling you can press the same Hint button in the toolbar as you pressed when you wanted checker play hint The hint window will again appear but this time it will look a bit different and it will show a hint of the correct cube decision GNU Backgammon Manual V0 16 24 82 SS GNU Backgammon Hint ota Cube analysis Cubeless 2 ply equity 0 089 Money 0 087 Win Whig wWibg Lose Lig L bg 0 523 0 170 0 006 0477 0 1530 0 007 Cubeful equities 1 Mo double 40 123 2 Double pass 1 000 0 877 D Double take 0 157 0 280 Proper cube action Mo double take 24 2 Eval 0 1 Figure 10 The cube hint window The first lines is the window dialog shows the evaluation depth and the cubeless equity with the evaluated probabilities This equity is compensated for the match score The cubeless equity for a money game where the the calculation of equity is not compensated for match score is also reported Next follow three lines with cubeful equities In figure above the cubeful equity for the player on roll for not doubling at this turn is 0 123 The equity for a double and the opponent passing is of course 1 000 since the player then will win one point The number is normalized to cube value of one so even if it is a redouble to 4 or 8 or higher t
10. MWC dead 1 x MWC live x as MWC is the entity that is used for match play evaluations 11 5 5 2 Live cube equities The live cube equity is the equity assuming that the equity changes continuously so that doubles and takes occurs exactly at the double point and take point For gammon free play this is the well known take point of 20 Janowski derives the more general formula TP L 0 5 W L 0 5 where W is the average cubeless value of games ultimately won and L is the average cubeless value of games ultimately lost For example for the following position Figure 28 Cubeful example 1 GNU Backgammon evaluates Win W g W bg L g L bg static 0 454 0 103 0 001 0 106 0 003 and hence W 0 454 0 103 0 001 0 454 1 229 and L 0 556 0 106 0 003 0 556 1 196 For gammon free positions e g a race W 1 and L 1 The live cube equity is now based on piecewise linear interpolation between the points 0 L TP 1 CP 1 and 100 W if my winning chance is 0 I lose L points at my take point I lose 1 point at my cash point I cash 1 point and when I have a certain win I win W points GNU Backgammon Manual V0 16 62 82 Wins Figure 29 mgtp For match play there is no simple formula since redoubles can only occur a limited number of times The live cube take point is generally calculated as TP live n Cube TP dead n cube 1 TP live 2n cube So to calculat
11. Note that the cube decision pull down menu will only be visible when the player has the cube available The next pull down menu shows a simple analysis of the roll The roll in this position was 32 GNU Backgammon s evaluation of this dice roll is also empty It shows that this particular roll was 162 equity worse than the average roll This means that the roll is a bit unlucky but does not qualify for being marked as an unlucky roll The rolls are marked in these categories Very lucky Lucky Unlucky and Very unlucky The rightmost pull down menu shows the move which was done In this situation the move that was done was 3 off 2 off This move did not qualify for any mark Moves that GNU Backgammon don t like will be marked as Doubtful Bad or Very bad The user can also override GNU Backgammon s evaluation and mark the move manually with the pull down menu The rest of the analysis window is a notebook of two pages The first page is the list of possible moves The list is sorted in the ranked order with the best considered move at the top The moves are sorted by equity or EMG In the list in the figure there is only two possible moves The move that was actually done in the match is marked with red color The only difference of this list of moves and the list of moves in the hint window is that this list does not show the probabilities for each outcome of the game If you want to see the probabilitie
12. color The checkers move decisions are shown by the font color Cube background Move font Very Bad Yellow Red Bad Pink Blue Doubtful Grey Green The luck is also marked in the font Luck Font Very Lucky Bold Very Unlucky Italics 8 4 2 Analysis panel You can also study your moves and cube decisions in more detail in the analysis window or analysis panel if you have checked Dock panels in the Window menu You can open this window by checking on Window Analysis If you have docked panels the analysis panel will appear under the game record The analysis window is basically the same as the Hint window described in the Playing a game or match chapter GNU Backgammon Manual V0 16 38 82 Didn t double Rolled 32 0 1621 Mowed 30 2 40FF Chequer play Cube decision Rank Type Equity Dif Move 1 Cubeful2 ply 0 282 Sof 2 a 2 Cubeful2 ply 0 326 0 044 3 1 2fofF la US Figure 19 The Analyze pane In the figure you can see the analysis panel At the top of the analysis panel you will see three pull down menus The leftmost pull down menu is a comment on the cube decision In the figure it is a position where the player didn t double and the GNU Backgammon s analysis of this is empty There was nothing wrong with not doubling in this position The user can also override GNU Backgammon s evaluation and mark the cube decision as Doubtful Bad or Very bad
13. 4 2 Accepting or declining a cube ee 21 45 ReSIGDING 44 58 hb er pee haw gd en bdawe bode ba eeee dnt e ete woe A eee ee 21 4 5 1 Offeringaresignation e e so ese ceses iese emete tetere RRR RRR 21 4 5 2 Accepting or declining aresignation 2 ee 22 5 Getting hints and Tutor Mode 22 Si Getting hintsmanually lt cecce am RAE Si eR AE A Ee e N ee A ee E 22 5 1 1 Getting checker play hints while playing oaa ee 22 5 1 2 Getting cube decision hints while playing e 23 5 1 3 The hint tool buttons 0 000 2000000002 RRR RRR RR 24 52 Tutor mode ss al ee eee ee we Sa ee ed a eee ee ba eee a ow ed A 25 GNU Backgammon Manual V0 16 5 82 6 Time controls 26 7 Setting up a position 26 71 Entermg Editmode s 2 bo Bee A De RRR wee RR ew ee ee ee 26 TZ Editing sy aa ee es Cae eS eR SEALS eH RERREES RES A Yee SEALS Gx 26 7 3 Clearing the board s 2 so sna aos ae ee ee A Oe aOR OR ARA bee eee oe ee ewe 27 TAs Quickedit s mined e e ye he Ais Spe pk AE Oe Re ER hae Bee edd ee ye Sh ae ee 28 7 3 Editing by drag and drop s 4 2 6 2 2584 A E REA De AE EERE S AAA ox 28 7 6 Setting the player on turn lt sss RKR ee ee ee 29 7 7 Setting thedice e R RRR e ee SS ee we ee A e a a ee ss e 29 78 GTH the Cube Lita xz wee wees eM ee eS ee Ee wee WAS See ts Pewee geese Sx 30 7 9 Setting the score bee Oka hee eee Sa eA hae ede ed ee A eae 30 7 10 Exiting Edit mode 2 5 4 Segoe e Re EO AR ke oe Oe E Bae es
14. File sgg GamesGrid Save Game tmg TrueMoneyGames txt Snowie Text e Python Scripting ability e Native language support 10 languages complete or in progress cs_CZ da_DK en_GB en_US fr_FR de_DE is_IS it_IT ja_JP and tr_TR Note Some language translations are not completed yet 1 1 GPL copying warranty info GNU Backgammon is developed under the GNU General Public License GPL and it s part of the GNU project If you want to know more about GPL and the Free Software Foundation you can visit the FSF website 2 Rules of the game This section describes how to play a game a match or a session of money games against GNU Backgammon or a human opponent Authored by Tom Keith Skilled backgammon players may skip ahead to next section 2 1 Setup Backgammon is a game for two players played on a board consisting of twenty four narrow triangles called points The triangles alternate in color and are grouped into four quadrants of six triangles each The quadrants are referred to as a player s home board and outer board and the opponent s home board and outer board The home and the outer boards are separated from each other by a ridge down the center of the board called the bar GNU Backgammon Manual V0 16 13 82 Outer Board Red s Home Board o Outer Board White s Home Board Figure 1 A board with the checkers in their initial position An alternate arrangement is the reverse of the one shown
15. IL 0 491 Correct cube action No double beaver 11 2 Match Equity Tables It s possible to use several different match equity tables with GNU Backgammon 11 3 Python scripting Accessing the GNU Backgammon Python shell To access the Python shell either type gt from the command line or select Window Python Shell IDLE from the GUI GNU Backgammon Manual V0 16 57 82 11 3 1 gnubg module functions board command cmd evaluate evalcontext eq2mwc mwc2eg cubeinfo met positionid positionfromid positionkey positionfromkey positionbearoff positionfrombearoff navigate next N game N Match navigation Without any arguments go to first move of first match With next N move forward N game records With game N move forward backward N games Navigate never wraps around On success returns None If unable to complete the requested number of moves returns a pair of next remaining game remaining match analysis 1 0 boards 1 0 statistics 0 1 verbose 0 1 Return the current match For example gt m gnubg match Takes the following optional keyword arguments analysis When 0 discard analysis data default is 1 boards When 1 add current board to move double records Default is 1 statistics When 1 include game and match statistics Default is 0 verbose When 1 include derived analysis values Default is O GNU Backgammon Man
16. If an opposing checker lands on a blot the blot is hit and placed on the bar Any time a player has one or more checkers on the bar his first obligation is to enter those checker s into the opposing home board A checker is entered by moving it to an open point corresponding to one of the numbers on the rolled dice For example if a player rolls 4 and 6 he may enter a checker onto either the opponent s four point or six point so long as the prospective point is not occupied by two or more of the opponent s checkers GNU Backgammon Manual V0 16 15 82 Figure 4 White rolls 64 with a checker on the bar If White rolls 64 with a checker on the bar he must enter the checker onto Red s four point since Red s six point is not open If neither of the points is open the player loses his turn If a player is able to enter some but not all of his checkers he must enter as many as he can and then forfeit the remainder of his turn After the last of a player s checkers has been entered any unused numbers on the dice must be played by moving either the checker that was entered or a different checker 2 5 Bearing Off Once a player has moved all of his fifteen checkers into his home board he may commence bearing off A player bears off a checker by rolling a number that corresponds to the point on which the checker resides and then removing that checker from the board Thus rolling a 6 permits the player to remove a checker fr
17. a 31 TeL1 Analyzing the position errata oti ge we wa Se Eads eee OSS Rae A ox 31 8 Working with matches 31 8 1 Retrieving and storing backgammon files oaa 000000000000 0002222 31 8 1 1 The Smart Game Format 31 8 1 2 Opening and importing matches ee 31 8 1 3 Saving and exporting positions games or Matches e 32 8 1 3 1 HTMIL expOrt s ee ee ER ea ee a ae ee ee a ee e 32 8 1 3 2 LaTeX export ocs seya se Se ER Rw RRR eR Re ee ea ee a 33 8 2 Entering live tournament matches 33 8 2 1 Enteringillegalmoves a e a a RE a RRR e a EA RE e 9 34 8 3 Analyzing matches lt s o cssc 58 Deeb a ES eS ER ee ee ee ee 34 321 Analysis Settings 2 4 28S eR ee ES OHA EE Ba R See ea Pew ee ge ee ox 34 84 Reviewime Matches 6a a cha ee ee REA OPS RE OEE E eee eee eee a ew ws 36 84 1 Gamerecotd o e pr ecoa aa is Ne ee RRS Re Pee be ee aa e 36 84 2 Analysis pane xix 4 2 6 2268S ee Se ES ee eae eA AS AAA oa 37 SAS Statis l 2 4 6 pee ea be ee OE ER ae ede eb ORAM E 39 8 4 3 1 Checker play statistics 2 ee 39 8432 L ckanalysis vanes dm eet tit oe ed were ew A eee pe eet amp 4 39 84 3 3 Cuberstatistics s siec sy mes t ea ee ae ee ee ea eae ee 40 8 434 Overall rating i s ce eS ee RR EER a ee we a 40 9 Rollouts ai 9 1 Introduction to rollouts s ea e eee ee hea Se eH E BA Oe eS ee ee oS A 41 9 2 RolloutsinGNU Backgammon 42 9 2 1 Quasi Random Dice ppe e ee 42 GNU Backgammon Manual V0 1
18. a default set of images available from the gnubg org web site If you want to have html images locally on your computer you can have GNU Backgammon generate these The html images will be generated based on the current appearance settings You can also control the size of the images in the export settings dialog To get the export settings dialog you can select in the menu Settings Export Select the size of your html images at the bottom right in this dialog To start the generation of the html images select in the menu File Export HTML images In the file dialog box you can select a directory where the images will be generated The images are stored in PNG format To generate images for the command line use the command export htmlimages directory where directory is the directory where you want your images to be created 8 1 3 2 LaTeX export GNU Backgammon can export games match and positions to the document typesetting system LaTeX For exporting a match or session to LaTeX The LaTeX export will export all board diagrams and analysis if available The produced documents can therefore be quite large Note that the LaTeX file produced needs the eepic package You can get this package at your nearest CTAN mirror The produced LaTeX file also needs epic textcomp and ucs but these are more common in LaTeX distributions so you probably already have these You can not export a position to LaTeX At least not yet Howe
19. adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work In the combination you must combine any sections Entitled History in the various original documents forming one section Entitled History likewise combine any sections Entitled Acknowledgements and any sections Entitled Dedications You must delete all sections Entitled Endorsements H COLLECTIONS OF DOCUMENTS You may make a collection consisting of the Document and other documents released under this License and replace the indi vidual copies of this License in the various documents with a single copy that is included in the collection provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects You may extract a single document from such a collection and distribute it individually under this License provided you insert a copy of this License into the extracted document and follow this License in all other respects regarding verbatim copying of that document AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works in or on a volume of a storage or distribution medium is called an aggregate if the copyright resulting from the compilation is not used to limit the legal rights of the compilation s users beyond what the individual works permit When the Document is included in
20. an aggregate this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document If the Cover Text requirement of section 3 is applicable to these copies of the Document then if the Document is less than one half of the entire aggregate the Document s Cover Texts may be placed on covers that bracket the Document within the aggregate or the electronic equivalent of covers if the Document is in electronic form Otherwise they must appear on printed covers that bracket the whole aggregate J TRANSLATION Translation is considered a kind of modification so you may distribute translations of the Document under the terms of section 4 Replacing Invariant Sections with translations requires special permission from their copyright holders but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections You may include a translation of this License and all the license notices in the Document and any Warranty Disclaimers provided that you also include the original English version of this License and the original versions of those notices and disclaimers In case of a GNU Backgammon Manual V0 16 82 82 disagreement between the translation and the original version of this License or a notice or disclaimer the original version will prevail If a section in the Document is Entitled Acknowledgements Dedications or Histo
21. are the quickest way to start the game or match If you click on the button with the sign you will start a new money game session immediately If you click on a numbered button you will start a new match of the specified length The dialog allows a fine tuning of the startup options 1 Use the radio buttons to choose whether you want to start a match game or session If you wish to start a new match you should select the match length by typing into the Match length field 2 You may play against both the program itself or against a friend If you want to start a match or game against a friend select the Human vs Human option 3 Normally the dice are generated by a random number generator but you may use manual dice if you check this option Then GNU Backgammon will prompt for the dice roll before each roll 4 GNU Backgammon comes with a tutor mode If this mode is active GNU Backgammon analyzes each move you do and warn you each time you make a mistake More about tutor mode later 5 By clicking on the Modify player settings button you will see the whole player setting dialog Here you define the playing strength of GNU Backgammon This dialog will be explained later 4 2 Rolling the dice The simplest way to roll the dice is to click in the right board area between the board points You can also roll the dice from the menu Game Roll or with the keyboard shortcut Ctrl R GNU Backgammon Manual V0 16 20 82 20 21
22. calculate all the possibilities 2 plies ahead and evaluate them allowing it to find better moves Since Supremo is a 2 ply setting we are only interested in the 2 ply settings of Large as in the figure above 3 ply or 4 ply settings will have no effect here because Supremo doesn t examine at that depth In the figure above we can see it first will Always accept 0 moves This first line means that it won t force any moves to be analyzed at 2 ply it will only analyze moves according to the second line If it had said it would always analyze 2 moves this would mean that no matter how ridiculously bad the 2nd move was compared to the Ist it would analyze both at 2 ply The second line says it will Add extra 16 moves within 0 320 This means that provided they aren t more than 0 320 equity worse than the top move it will select a maximum of 16 moves to analyze at 2 ply For example in the figure below the 2nd best move is no less than 0 453 equity worse than the top choice so it didn t bother analyzing them at 2 ply as it is unlikely to change its mind on what the best move is 1 Cubeful O ply 20 6 11 0 Dz 494 16 4 0 2 0 131 Bist 6 5 Rank Type Win Wg Wha Lose Lal La Ea Dif Move 2 CubefulO ply 36 8 6 0 0 1 63 2 23 9 0 4 0 322 453 20 16 3 CubefulO ply 34 6 5 7 0 1 65 4 28 5 0 5 0 424 0 555 13 9 Figure 23 Move filter 2 Take a look at next figure GNU Backgammon Manual V0 16 50
23. exports in validating XHTML 1 0 with the use of CSS style sheets You may add your own style sheet to the exported HTML files if you wish to override the default layout e g change colors or fonts The board is made up from hundreds of pictures Currently you can choose between three different sets of pictures 1 the BBS images used by Kit Woolsey s GammOnLine e magazine Danish Backgammon Federation s web based discus sion group and others 2 the fibs2html images used by the Joseph Heled s program fibs2html 3 images generated by GNU Backgammon itself The images generated by GNU Backgammon will use your current board design in GNU Backgammon and honors your settings on clockwise or anti clockwise movement and board numbering on off dynamic If you export a match or session to HTML GNU Backgammon will write the individual games to separate files For example if you export to file foo html the first game is exported to foo html the second game to foo_002 html the third game to foo_003 html and so forth The output from the HTML export can be customized For example it s possible to leave out the analysis or parts of the analysis Also you may enter a specific URL to the pictures used to compose the board which is useful for posting positions on web based GNU Backgammon Manual V0 16 33 82 discussion groups such as Kit Woolsey s GammOnLine the Danish Backgammon Federation s Debat Forum or you may opt to use
24. in the unit circle and add to each possible outcome probability This means that the addition is random but distributed so that it s more likely to have an noise addition close to zero than a noise addition close to the limit The noise addition is limited to the number you put into the noise field in the dialog box If you check the box Deterministic noise the noise added to each evaluation will be based on a sum of the bytes in the hash of the board position which by the central limit theorem should have a normal distribution In that way you will always have that same noise amount to a position since the noise added to the evaluation is only depending on the position itself If you want GNU Backgammon to evaluate and play as strong as possible you should not add any noise 10 2 Appearance You can change the appearance of GNU Backgammon There is a lot of options to choose among and you can have the board look like nearly anything This section will help you through some on the appearance customization To change the look of the board you should click Settings Appearance This will open a dialog box like this GNU Backgammon Appearance Oak and Maple by Ausbilder Schmidt predefined Lighting Designs Chequers Board Border L Display Type 3d Options gt 5 2d Board T Show shadows 1 3d Board light LT dark F Animate dice rolls Y Numbered point labels F Animate resignation fag Dynamic labels Y Close bo
25. moves and return to the position before any checkers have been moved You can either click the Undo button in the toolbar or you can choose Edit Undo from the menu or the keyboard shortcut Ctrl Z 4 3 4 Some shortcuts There are some shortcuts for moving the checkers You can make a new point by right clicking on the empty point that you want to make As an example if you roll 31 as the opening roll and you want to play 8 5 6 5 you simply place the mouse cursor on the 5 point and right click Making points this way also works if you hit a checker and with doubles Another shortcut can be used in the bearoff phase of the game By clicking in the bearoff tray two checkers will be born off if such a move is legal GNU Backgammon can auto play forced moves for you This feature can be enabled by choosing Settings Options Game and then check the box Play forced moves automatically 4 4 Using the double cube 4 4 1 Offering a double You offer a double to your opponent by clicking on the cube This will offer the cube immediately You can also click Game Double from the menu or the keyboard shortcut Ctrl D 4 4 2 Accepting or declining a cube You accept a double made by your opponent by clicking on the offered double cube at the board If you want to decline the double you can right click on the cube There are also three buttons in the toolbar for handling cube offers These buttons are marked Accept Decline and Beav
26. number in this field However if you want to analyze further moves in a particular position it s not a problem to do that later The move that was actually done in the match will be analyzed even if 1t is ranked below the number of moves limit GNU Backgammon will also mark each move or cube decision with Doubtful Bad and Very bad You can adjust the limits in equity difference for which label to assign This is done in the frame box to the left Notice currently the Good and Very good classes are not used You can also adjust the classes for what GNU Backgammon considers lucky and unlucky rolls The luck of a roll is defined as the difference of equity after the best move after rolled dice and the equity after best move averaged over all possible rolls The right part of the dialog box is an evaluation setting for how each move or cube decision should be evaluated in the analysis For an explanation of this settings see the chapter called Evaluation settings GNU Backgammon Manual V0 16 36 82 8 4 Reviewing matches 8 4 1 Game record When a match is analyzed in GNU Backgammon you should open the game record window Open this by checking Window Game record on from the main menu The game record window can also be docked into the right side panel If you want it docked into the right side panel you should check on Window Dock panels The game record window shows a list of all the moves in the game You can also navigate be
27. out the string to 80 bits with Os The worst case representation will require 80 bits you can see that there are always 50 0 bits even if there are no checkers at all Each player has a maximum of 15 checkers in play not yet borne off which require a bit wherever they are positioned That s 30 bits to take of all checkers plus the 50 bits of overhead for a total of 80 bits the last bit is always 0 and isn t strictly necessary but it makes the code slightly easier This bit string should be stored in little endian order when packed into bytes i e the first bits in the string are stored in the least significant bits of the first byte As an example here s what the starting position looks like in the key format 00000 player on roll has no checkers on ace to 5 points 111110 5 checkers on the 6 point 0 empty bar 1110 3 on the 8 0000 no others in our outfield 111110 5 on the midpoint 00000 none in the opponent s outfield 00000 or in opponent s board until GNU Backgammon Manual V0 16 66 82 110 two on the 24 point 0 none on the bar 00000 opponent has no checkers on ace to 5 points 111110 5 checkers on the 6 point 0 empty bar 1110 3 on the 8 0000 no others in opponent s outfield 111110 5 on the midpoint 00000 none in our outfield 00000 or in our board until 110 two on the 24 point 0 none on the bar so altoget
28. second model is not published but redefines the cube efficiency into a value that can be understood more intuitively and calculate easily from rollouts 11 6 A technical description of the Position ID This section describes a method for compactly recording a backgammon position It demonstrates how to encode a position into 10 binary bytes which is useful for minimizing the space used when recording large numbers of positions in memory or on disk There is also an ASCII representation in 14 characters which is convenient for output to the screen for copying and pasting to transfer positions between programs which support the format and for communicating positions via Usenet news or e mail The 10 byte binary format is called the key and the 14 character ASCII format is the ID The key is essentially a bit string imagine you start with an empty sequence of bits and continue adding either 0 or to the end The way to build up a sequence that corresponds to a given position is 1 For every point around the board starting at the ace point of the player on roll continuing around to the 24 point and ending at the bar 2 append as many 1s as the player on roll has on that point if any 3 append a 0 4 For every point around the board starting at the ace point of the opponent continuing around to the opponent s 24 point and ending at the bar 5 append as many 1s as the opponent has on that point if any 6 append a 0 7 Pad
29. so he can play on for a gammon 2 9 Rules for Match Play When backgammon tournaments are held to determine an overall winner the usual style of competition is match play Competi tors are paired off and each pair plays a series of games to decide which player progresses to the next round of the tournament This series of games is called a match Matches are played to a specified number of points The first player to accumulate the required points wins the match Points are awarded in the usual manner one for a single game two for a gammon and three for a backgammon The double cube is used so the winner receives the value of the game multiplied by the final value of the double cube Matches are normally played using the Crawford rule The Crawford rule states that if one player reaches a score one point short of the match neither player may offer a double in the immediately following game This one game with no doubling is called the Crawford game If the Crawford game is won by the trailing player then the double cube becomes available in all subsequent games and it s most often in the best interests of the trailing player to double immediately in these games Match to 5 White Black Doubling White wins 2 2 0 Allowed Black wins 1 2 1 Allowed White wins 2 4 1 Allowed Black wins 1 4 2 Crawford Game Black wins 2 4 4 Allowed White wins 2 6 4 Allowed GNU Backgammon Manual V0 16 17 82 In
30. that is not Transparent is called Opaque Examples of suitable formats for Transparent copies include plain ASCII without markup Texinfo input format LaTeX input format SGML or XML using a publicly available DTD and standard conforming simple HTML PostScript or PDF designed for human modification Examples of transparent image formats include PNG XCF and JPG Opaque formats include proprietary formats that can be read and edited only by proprietary word processors SGML or XML for which the DTD and or processing tools are not generally available and the machine generated HTML PostScript or PDF produced by some word processors for output purposes only The Title Page means for a printed book the title page itself plus such following pages as are needed to hold legibly the material this License requires to appear in the title page For works in formats which do not have any title page as such Title Page means the text near the most prominent appearance of the work s title preceding the beginning of the body of the text A section Entitled XYZ means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language Here XYZ stands for a specific section name mentioned below such as Acknowledgements Dedications Endorsements or History To Preserve the Title of such a section when you modify the Document means that it remains a sec
31. the next dice roll If your in the move list where the dice is not rolled a click on this green Next button will show you the same position with the dice rolled The last two buttons take you to the next marked move or to the previous marked move The green arrow button with a question mark pointing to the left will take you to the previous marked move The green arrow button with a question mark pointing to the right will take you to the next marked move You can also go to other games in the match or session by selecting the game in the game drop down menu You can also go to a move directly by clicking that move in the game record list There is also some keyboard shortcuts for navigating through the match Page Down till take you to the next move and Page up will take you to the previous move GNU Backgammon Manual V0 16 37 82 After a analysis some of the move in the game list will be marked You will see some moves marked with and some with 77 and some with These marks means the same as the marks in normal chess notation 2 a very bad move 2 a bad move a doubtful move Note that it is the same marks for cube decisions as for checker moves Nevertheless checker moves marks are before the cube decisions marks If no mark exists for checker move the cube mark is separated by two spaces In newer builds of GNU Backgammon the various moves also get a color code The cube decisions are shown by the background
32. the number of trials 1s proportional to 46656 Suppose a user stops a 1296 trial rollout after 36 games The 36 games would have had the following rolls for the first two rolls of each game 11 11 21 11 12 11 31 11 13 11 66 11 Obviously such a rollout will give skewed results since the second roll was 11 for all games To avoid this problem GNU Backgammon will randomize the sequence of rolls such that it is guaranteed that for any sample of 36 games you have exactly one game with first roll 11 exactly one game with second roll 11 etc This is called stratification GNU Backgammon will actually also rotate and stratify rollouts where the number of trials are not multiples of 36 1296 etc The distribution of rolls is obviously not uniform any longer in this case but it will still provide some reduction of the luck i e no 37 trial rollout will have 3 games with a initial 66 Before the first game of a rollout GNU Backgammon creates a pseudo random array which it will use for all the games in the rollout In effect it has already decided the roll sequence it will use for up to 128 rolls in every game of the rollout In other words for a normal rollout where games don t go over 64 moves every single game of every possible rollout length has already had its dice sequence determined During the rollout of game n sequence n will be used for game n 1 sequence n 1 etc If it s a rollout as initial position then whenever the current sequen
33. uses the values 0 6 0 7 originally suggested by Rick Janowski Position Class x Cube efficiency Two sided exact bearoff n a One sided bearoff 0 6 Crashed 0 68 Contact 0 68 Race linear interpolation between 0 6 and 0 7 For race GNU Backgammon uses linear interpolation based on pip count for the player on roll A pip count of 40 gives x 0 6 and 120 gives x 0 7 If the pip count is below 40 or above 120 values of x 0 6 and x 0 7 are used respectively For the two sided bearoff positions the cubeful money equity is already available from the database so for money game there is no need to calculate cubeful equities via Janowski s formula However the cubeful equities for money game cannot be used for match play Instead of using a fixed value of x say 0 6 GNU Backgammon will calculate an effective value based on the cubeful money equity The cubeful MWC is calculated as usual but with the calculated x There is obviously room for improvements For example holding games should intuitively have a lower cube efficiency since it s very difficult to double effectively either it s not good enough or you ve lost the market by a mile after rolling a high double or hitting a single shot Similarly backgames will often have a low cube efficiency whereas blitzes have may have a higher cube efficiency 11 5 5 6 Cube decisions GNU Backgammon s cube decisions are simple based on calculations of cubeful e
34. 0 011 0 229 0 006 0 240 0 009 0 238 0 009 0 415 0 474 0 510 0 530 0 559 0 578 0 589 0 614 0 388 0 446 0 483 0 502 0 532 0 551 0 562 0 587 18 15 13 11 13 11 6 3 18 13 11 8 6 4 13 11 13 10 11 6 13 8 18 15 11 9 Move Figure 9 The hint window This Hint window shows a list of all possible moves for the position and dice roll The different moves are sorted by how GNU Backgammon ranks each move there is one move on each line in the list The rest of the numbers may look a bit complicated and cryptic but once you learn what each number means it isn t really that bad 1 Rank is the number that shows GNU Backgammon s rank of the move All moves evaluated at a given ply are ranked above those evaluated at a lesser ply If you use the 0 1 2 etc buttons below the hint list to re evaluate one or more moves the GNU Backgammon Manual V0 16 23 82 moves will be moved accordingly Therefore for accurate results when re evaluating a move that you are interested in it is usually best to re evaluate all moves above it in the list And slipping with the mouse and re evaluating e g a 3 ply move at 2 ply may make the move disappear down to the bottom of the list 2 Type is a description of the evaluation that was used to calculate the results Cubeful means that it is taking into account the possibility that someone may double Occasionally you may see several moves with the equity of
35. 1 000 See Equity below despite significantly different winning percentiles This is because it thinks that if any of these moves are played then the opponent will double and you should pass The n ply is the depth to which GNU Backgammon analyzed the move 3 Win is the fractions of games that GNU Backgammon thinks will be won by a single game gammon or backgammon Wg is the fractions of games that GNU Backgammon thinks will be won by a gammon or backgammon Wbg is the fractions of games that GNU Backgammon thinks will be won by a backgammon NH Nn A Loose is the fractions of games that GNU Backgammon thinks will be lost by a single game gammon or backgammon Notice that this number is equal to 1 Win 7 Lg is the fractions of games that GNU Backgammon thinks will be lost by a gammon or backgammon 8 Lbg is the fractions of games that GNU Backgammon thinks will be lost by a backgammon 9 Equity is the overall evaluation of the position by the program after considering the different win loss percentiles the cube position and the match score A 1 000 would mean that you are expected to win a point a 0 000 would mean that it is roughly equal and a 1 000 that you are expected to lose a point When the evaluation is cubeful this number is not computable by the win loss brake down of the previous columns 10 Diff is the difference in equity perceived in comparison to the top ranked move 11 Move is the move being evaluated
36. 22 23 M By Figure 7 Click in the red rectangle to roll the dice When you have moved your checkers to make the desired move you complete your turn by clicking on the dice 4 3 Moving the checkers 4 3 1 Moving by drag and drop One way to move the checkers is to click on a checker you want to move and then drag it while holding the mouse button down to the desired designation point If you have the option Show target help when dragging checkers enabled you will see the a green guiding at any legal target point for the checker you are dragging You can find this option by choosing Settings Options Display 4 3 2 Moving checkers by clicking Move the mouse cursor over the checker you want to move If you now click the left mouse button the checker will move the pips of the left die If you have already moved one checker clicking on a new checker will move it according to the pips of the remaining die If you click with the right mouse button on a checker the checker will move according to the right die Using this method for moving the checkers can be really effective Some users prefer showing the higher die to the left You can make GNU Backgammon show the highest die to the left if you choose Settings Options Dice and check the check box labeled Show higher die on left GNU Backgammon Manual V0 16 21 82 4 3 3 Undo a move Before you complete your move by clicking the dice it s possible to undo your
37. 6 10 Customizing GNU Backgammon 10 1 Evaluation settings 10 1 1 10 1 2 10 1 3 10 1 4 10 1 5 10 1 6 10 1 7 10 1 8 10 1 9 10 1 10 Move filters 10 1 12 Reduced evaluations 10 1 13 Pruning neural networks 10 1 14 Noise 10 2 Appearance Introduction to evaluation settings The depth to search and plies o Defining evaluation settings o o PlayinesSKIlE omic Analysis ee o i a a wR ee Ew a eS RollOU S o aia R R R E a ah a GE R Changing evaluation settings a Predefined settings o e eee eee 10 1 10 1 Introduction to move filters 10 1 10 2 Defining move filters o 10 1 11 Cubeful vs Cubeless 11 Technical Notes 11 1 Obtaining bearoff databases 11 1 1 11 1 2 11 1 3 11 1 4 11 1 5 11 1 6 11 2 Match Equity Tables 11 3 Python scripting 11 3 1 11 3 2 11 3 3 11 3 4 11 3 5 11 4 Guile scripting 11 5 Equities explained 11 5 1 11 5 2 Generate your OWN 2 2 0 0 eee eee ee ee Download deis a be we SPOR E R e ia Verification of databases One sided bearoff databases compressed Two sided bearoff databases with cubeless and cubeful equities Two sided databases for Hypergammon gnubg module functions 0004 Match description e e Match M O a gos R Roe e RR a BO a E R Python game o se ces ocea oe ep e a 0 00000 T
38. 6 8 82 12 3 7 Ido not need this graphical stuff Where is the terminal for commands Ta 124 Playing Dackgamiinon s se R a RT Oe HRS EES EWA SEs ARAS a Ta 12 4 1 What is the difference of a new game or match or session o a T3 12 4 2 What the heck is a beaver in Backgammon oaaae 73 12 4 3 How do I move the checkers a 73 12 4 4 Why am I allowed to place more than 5 checkers on a point oa a a 12 4 5 GNU Backgammon plays poorly 2 2 2 a 73 12 4 6 GNU Backgammon is too strong for me ee Ta 12 4 7 I think the bot is cheating It always gets good dice oaa a 74 12 5 SOLD a ee es a e a E E A E a a PRESS Rae E a A a See a wae eo 74 12 5 1 Where can I change the name of the human player 74 12 5 2 How dolI change the colors ee 74 12 5 3 How do I stop the annoying beeps oaaae 74 12 54 What ate Phes orcos ee TR Re ee Pe ee we REA ee e 74 T What is DOISE 2 2 2 04 Be eee ee e dd ra ok 74 12 5 6 What is reduced evaluation 2 2 2 ee 74 12 6 ADA ZING aioe oe he Wee Bet ie Oe GAR dins amp Bas He BS A Gerd Boe Se had Y T5 12 6 1 What are these funny letters at the right bottom a Wes 12 6 2 How do I set up a position manually aoaaa a T 12 6 3 Which formats must I use to import matches and positions s oaoa oe a 75 12 6 4 How can I switch the players sides T3 12 63 Whatdo and Mean soc soe oe ee a 7a 12 6 6 Ho
39. 6 30 82 20 21 22 23 24 ti Figure 16 Click inside the red rectangle to set the dice for Black Click inside the green rectangle to set the dice for White Setting the dice in edit mode sets both dice and the player on turn Setting the dice for player 0 will make player 0 on turn with that specific dice roll to play This method for setting the dice roll only works in edit mode If you re not in edit mode you can set the dice by choosing Game Set dice from the menu however this will set the dice for the player on turn 7 8 Setting the cube Setting the cube is quite simple while you re in edit mode Simply click the cube in the board and the cube selection widget appears Selecting a cube in the first row where the number is displayed up side down the top player will be the cube owner The value of the cube will be the value of the cube you click in the widget Note that the unturned cube is the leftmost cube labeled 64 just as it usually is on real double cube 7 9 Setting the score Very often i backgammon the match score does matter on how the position is evaluated GNU Backgammon s evaluation algorithms does take the score into account You can therefore adjust the the match length and the score to each player while you re in edit mode In the figure you see that the score fields are editable while you re in edit mode Insert the desired match score for each player in these fields Player 0 the top play
40. 82 Predefined move filters user defined i ply 2 ply _3 ply 4 0 F Enable this level Always accept a 5 Moves Add extra 116 S moves within 320 S F Enable this level Figure 24 Move filter 3 Here the exact same settings were maintained but the 1 ply filter was activated This just means that those 16 moves selected from the O ply are sent instead to be analyzed at 1 ply and then up to 5 moves from 1 ply will be sent to be analyzed at 2 ply So this would actually be faster than the previous setting and weaker since a maximum of only 5 moves would be analyzed at 2 ply depth Tip Feel free to experiment with the settings as you can always reset them by simply choosing one of the predefined levels In order to see if they are better or as good but faster I d suggest comparing the results with Supremo One setting I have that works quite well is to take the basic Supremo setting and in the Move filter reduce the 16 to 12 It cuts down on the thinking time by 20 25 more or less and I haven t seen more than one case in over 10 000 moves where it missed the best move 10 1 11 Cubeful vs Cubeless In the evaluation settings dialog box you can specify whether or not checker play should be evaluated cubeful It s recommended that you use cubeful evaluation To get an understanding of what cubeful checker play evaluations are you can take a look at this position GNU Backgammon Manual V0 16 51 82 Figu
41. GNU Backgammon Manual V0 16 1 82 GNU Backgammon Manual V0 16 GNU Backgammon Manual V0 16 2 82 Copyright 1999 2000 2001 2002 2003 Achim Mueller Gary Wong Copyright 2007 Christian Anthon Feedback To report a bug or make a suggestion regarding the GNU Backgammon application or this manual send your suggestions to bug gnubg gnu org or make a bug report Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation with no Invariant Sections no Front Cover Texts and no Back Cover Texts A copy of the license is included in Appendix A GNU Backgammon Manual V0 16 3 82 COLLABORATORS TITLE REFERENCE GNU Backgammon Manual V0 16 ACTION NAME DATE SIGNATURE WRITTEN BY Christian Anthon November 16 2007 REVISION HISTORY NUMBER DATE DESCRIPTION NAME GNU Backgammon February 2007 GNU Backgammon Project Manual docbook version GNU Backgammon January 2007 GNU Backgammon Project Manual wiki version GNU Backgammon November 2003 GNU Backgammon Project Manual texinfo version GNU Backgammon Manual V0 16 4 82 Contents 1 Introduction 11 1 1 GPL copying warranty info 2 12 2 Rules of the game 12 Dab SEUD ino a ld id ee on Le eh Gh ee ee Os A r an Ae S ge ee eee a 12 22 Objector the Ga
42. NU Backgammon Manual V0 16 74 82 12 4 7 think the bot is cheating It always gets good dice In its default configuration the dice generator does not cheat In the menu Settings you may choose between different random dice generators If you still think GNU Backgammon is cheating program your own dice generator or roll manually It doesn t cheat 12 5 Settings 12 5 1 Where can I change the name of the human player Go to the menu Settings Players and click on Player 1 At the top there is a field to change the human player s name 12 5 2 How do I change the colors Go to the menu Settings Appearance Here you may change the color of checkers the points and the board itself 12 5 3 How do stop the annoying beeps Go to the menuSettings Appearance and click on the General tab at the right Disable the option Beep on illegal input 12 5 4 What are Plies A ply describes how far GNU Backgammon evaluates the position 0 ply means that GNU Backgammon estimates the worth of the position as it is A ply evaluation looks one step deeper i e it evaluates the position after making the best possible move for each of the 21 different rolls and returns the averaged result 2 ply is another roll further and so on The more plies you choose the more you strengthen GNU Backgammon Keep in mind that this will also decrease the playing speed Note also that 0 ply in GNU Backgammon is equivalent to the p
43. Odb19ab08feae 1feb33ddbd709479f62 6 6 44b6040b49b46cb9dd2ce8caa947044d 7 6 9eb8b042d4d2ddf8d40e74a892745ad5 8 6 fcdbbcs0b7ef84ddc81b839d0f26bed1 9 6 al1b2d410d51401143d05e73f9ffac15 10 6 12dc70c86f356d06bc96ee38dee40c62 11 6 not available 12 6 not available GNU Backgammon Manual V0 16 56 82 13 6 not available 14 6 not available 15 6 not available 11 1 6 Two sided databases for Hypergammon As the generation of the Hypergammon databases are an iterative process it s not possible to give MDS checksum for these as it depend heavily on your convergence threshold the number of restarts and rounding errors A random position from the database is found in Example 11 1 The equities and percentages in your own database should be very similar if not identical GNU Backgammon Position ID ADAAAQAKIAAAAA Example 11 1 Random position from hypergammon database GNU Backgammon Position ID ADAAAQAKTAAAAA Match ID CAKAAAAAAAAA 13 14 15 16 17 18 MORADOS A 2 AL O gnubg x X X 0 points v BAR Cube 1 O On coL O O O points S 0 gt 9 8 1 S 3 4 gt 1 ar Me Jue Player Opponent Position 3018 2881 Owned cube e 0 020 Centered cube e 0 23100 Centered cube Jacoby rule UA Opponent owns cube ISS Win W 9 W bg L g L bg Equity cubeful starles 0 456 0 244 0 014 omis 0019 O 168 OA Z LR No double E 0 2118 Double pass 2 DO FL 2 LO Double take D
44. You can also use the same toolbar buttons as for accepting or declining a double There is also a menu option for accepting and declining resignations Click Game Agree to resignation from the menu to accept an offered resignation Click Game Decline resignation from the menu to decline an offered resignation B Getting hints and Tutor Mode 5 1 Getting hints manually 5 1 1 Getting checker play hints while playing If you want to get a hint of the best move or the best cube action press the Hint button in the tool bar or the menu option Analyze Hint This will open a hint window GNU Backgammon Hint Rank Type win wa w bg Lose Lg Lbg Equity Diff Move i Cubeful O ply_0 513 0 094 0 002 0 487 0 147 0 004 0 027 18 164 11 8 Cubeful 0 ply Cubeful 0 ply Cubeful 0 ply 0 502 0 479 0 480 0 092 0 095 0 096 0 002 0 498 0 002 0 521 0 003 0 520 0 150 0 005 0 171 0 006 0 177 0 008 0 065 0 156 0 160 0 037 0 128 0 133 18 16 13 18 16 6 3 18 16 13 10 Cubeful 0 ply Cubeful O ply Cubeful O ply Cubeful O ply Cubeful O ply Cubeful O ply Cubeful O ply 0 376 Cubeful O ply 0 372 0 1 23 4 Rollout Show 0 415 0 400 0 387 0 391 0 385 0 374 0 067 0 074 0 066 0 075 0 076 0 069 0 073 0 069 0 001 0 585 0 002 0 600 0 001 0 613 0 002 0 609 0 002 0 615 0 001 0 626 0 001 0 624 0 001 0 628 MWC Temp Map 0 201 0 005 0 219 0 006 0 209 0 006 0 242 0 008 0 249
45. a eii eka eRe a BOS RES RR ADS eB ee ee Ra ee Ae E a 49 Move IGT ted Be de ei Eee aie ee RE Bi He es es ed eee es WES Ege he Be wd ts 4 50 Cubeful example s lt eee ee EH Oe ee ee A 51 Cubefol example 2 s s errar e E A RE EA e 32 Theappearancedialogi ce or dt a a E AS a At amp 4 53 Cubeful example L o cuoc 245 be ee eh ae ede Oe ee hee E bated ee E eae we 61 MSD rr A A a e e 62 TUNUP a AA A eR Ee e A Eee amp a 63 MECO e oh nea ee PA Rete eed eb ee OER eek be bea ded a ee eee 64 The double Me ey rss e oa eae E ce eae oP Ree E S TI Abstract The incomplete GNU Backgammon manual GNU Backgammon Manual V0 16 ee 1 Introduction This manual describes how to use GNU Backgammon to play and analyze backgammon games and matches It corresponds to version 0 16 devel updated in February 2007 GNU Backgammon gnubg plays and analyzes backgammon games and matches It is able to play and analyze both money games and tournament matches evaluate and roll out positions and more Driven by a command line interface it displays an ASCII rendering of a board on text only terminals but also allows the user to play games and manipulate positions with a graphical GTK interface GNU Backgammon is extensible on platforms which support Python File Edit View Game Analyze Settings Go Help DSR B yx 4d PD oo f 0 New Open Save Export Resign Undo Hint Edit Direction Stop Position ID mHPwAQywZ ABMA Match ID cIkZAAAAAAAA 11 lt
46. ackages 71 82 Look for warnings or errors during compiling If you still don t have a clue send a message to bug gnubg gnu org 12 2 7 On what CPU will GNU Backgammon run fastest Here is a list of CPU and Evaluations per second Analyze Evaluation Speed Feel free to add your CPU Evals sec CPU ea Mien RAM Os GNUBG Version AMD Sempron 28450 1 3000 1800 K8T800 A 1024 MB Win 2000 0 14 mingw MHz Intel Core Duo Mac mini Core lt 28000 1 66 GHz Duo 512 MB Win XP SP2 0 14 mingw 27000 a A penis eds 1024 MB Win XP SP2 0 14 mingw 735 1 7 GHz P 8 Celeron 331 2 66 Dell Dimension 26000 GHz 3100 512 MB Win XP SP2 0 14 3 devel Sempron 2800 24500 rev E6_at_2000 Asus K8V X 768 MB Win XP SP2 0 14 3 devel MHz 23000 P4 2 8 GHz Asus P4P800D 1024 MB Win XP SP2 0 14 3 devel 21759 A 20004 Acer Aspire 1522 512 MB Kubuntu 5 04 0 14 3 devel 32bit mode AMD Sempron 21500 1 3000 1800 K8T800 A 1024 MB Win 2000 0 14 3 devel MHz Athlon XP 2500 s 20120 _at_1833 Mhz MSI K7N Delta2 1024 MB Suse Linux 9 2 0 14 3 devel Pentium M 1 7 Sony Vaio 20200 GHz Z1XSP 512 MB FreeBSD 5 2 Intel Pentium M Sony Vaio 19515 0 8 GHz 2 PCG SRX51P 256 MB Fedora FC6 T3 0 14 3 devel 19200 a M16 TBM x41 1024 MB Win XP SP2 0 14 3 devel GNU Backgammon Manual V0 16 72 82 16900 P4 2 GHz 256 MB Win 2000 0 14 devel Sony Vaio S
47. ackgammon will report this number as 100 and 0 for the opposite situation Note that this number is biased towards the analyzing bot e g a 0 ply analysis a game between GNU Backgammon 2 ply and 0 ply will suggest that 0 ply is a favorite which it is clearly not For an unbiased measure use the luck adjusted result above Threshold for ratings Normalized total error rate per move Rating 0 000 0 002 Supernatural 0 002 0 005 World Class 0 005 0 008 Expert 0 008 0 012 Advanced 0 012 0 018 Intermediate 0 018 0 026 Casual Player 0 026 0 035 Beginner gt 0 035 Awful Please note The Normalized total error rate per move is multiplied by 1000 in the default settings 9 Rollouts 9 1 Introduction to rollouts The million dollar question is simple enough out of all the games that could result from playing this position how many do we win and how many of our wins and losses are gammons and how many are backgammons The model is exactly the same as if we had an urn with a googol balls in it it s a big urn and many of the balls have win written on them and some say gammon loss and if we look hard enough there are a few that read backgammon win and so on Balls and urns are to probability theorists what teapots and checkerboards are to computer graphics researchers or squeamish ossifrage is to cryptographers they seem to come with the territory Instead of having the patience t
48. ahead evaluations it can reduce errors by making use of the equity difference from one ply to the next This can be interpreted as either canceling out the estimated luck i e the difference in equity evaluations before and after rolling or using subsequent evaluations to estimate the error in prior ones the two views are equivalent GNU Backgammon automatically performs variance reduction when looking ahead at least one ply 7 Stratified sampling uses quasi random number generation instead of pseudo random number generation this is a standard technique in Monte Carlo simulations where having a near perfect uniform distribution in your sample is more important than unpredictability GNU Backgammon only stratifies the first 2 plies of a rollout though it would be easy enough to extend it to the remainder 9 2 1 Quasi Random Dice Quasi Random Dice are used to reduce the element of luck in rollouts Instead of selecting purely random dice GNU Backgam mon will ensure a uniform distribution of the first roll of the rollout If 36 trials are requested one game will start with 11 two games with 21 two games with 31 etc In general if n 36 games is requested n games will start with 11 2 n games with 21 etc This is called rotation of the first roll Similarly if n 1296 trials is requested the second roll will be rotated such that n games will start with 11 11 n games with 11 21 n games with 21 21 etc The third roll be also be rotated if
49. ain If your Edit button in the toolbar is disabled it is because there is no game or match in progress With the current state of GNU Backgammon there must be a game or match in progress to be able to enter edit mode This may change in the future If there is no game in progress and you want to set up a position you can simply start a new game or match by clicking New in the toolbar When you are in edit mode you will see the the text Editing in the match information box below the board 7 2 Editing Setting up a position is basically done by editing the current position The editing it self is controlled by clicking different areas of the board and may not be obvious at first hand GNU Backgammon Manual V0 16 27 82 7 3 Clearing the board In edit mode you can easily clear the board by clicking in one of the bearoff trays It s often easier to start setting up a position with a empty board so this feature is really handy When you click on one of the bearoff tray all checkers will be moved to the bearoff Figure 13 Click in the one of the areas marked with a red ellipse to clear the board You can also just as easy generate the initial position by clicking the opposite trays when in edit mode Clicking in one of these trays puts all checkers back to the initial position GNU Backgammon Manual V0 16 28 82 Figure 14 Click in the one of the areas marked with a red ellipse to get to the initial position Note
50. ally for works whose purpose is instruction or reference C APPLICABILITY AND DEFINITIONS This License applies to any manual or other work in any medium that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License Such a notice grants a world wide royalty free license unlimited in duration to use that work under the conditions stated herein The Document below refers to any such manual or work Any member of the public is a licensee and is addressed as you You accept the license if you copy modify or distribute the work in a way requiring permission under copyright law A Modified Version of the Document means any work containing the Document or a portion of it either copied verbatim or with modifications and or translated into another language A Secondary Section is a named appendix or a front matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document s overall subject or to related matters and contains nothing that could fall directly within that overall subject Thus if the Document is in part a textbook of mathematics a Secondary Section may not explain any mathematics The relationship could be a matter of historical connection with the subject or with related matters or of legal commercial philosophical ethical or political position regarding them The Invariant Sections are certai
51. ard on exit 0 Board angle L 20 FOY skew LL Plan view Y Show move indicator Curve accuracy low high Dice size small Pe large Quick drawing Test performance fx Figure 27 The appearance dialog In this dialog box you see a preview picture of the board at the right side and you have notebook with options to the left There are two different board rendering engines in GNU Backgammon It s a 2 dimensional rendering engine which is simple and fast but still makes really good board images The moves can be animated The other board rendering type is a 3 dimensional board engine based on OpenGL This board rendering engine makes astonishing fine board graphics and animates the rolls and moves beautifully You can even add textures to your boards and checkers However the 3D rendering type need a good modern graphic card which can take 3D hardware acceleration The leftmost tab in the appearance settings notebook is the General option You can here select between the 2D board or the 3D board You can also choose between different other settings Most of the settings here are self explanatory GNU Backgammon Manual V0 16 54 82 Warning Don t forget to save your settings A lovely and painstakingly crafted board setup can be lost if you don t faithfully do your Settings Save settings 11 Technical Notes 11 1 Obtaining bearoff databases 11 1 1 Generate your own GNU Backga
52. be MWC to be 29 2 Using a value of x 0 68 we arrive at a cubeful MWC of 29 17 11 5 5 4 n ply Cubeful equities The previous section concerned the calculation of 0 ply cubeful equities so how so GNU Backgammon calculate cubeful 2 ply equities The answer is by simple recursion Equity 0 Loop over 21 dice rolls Find best move for given roll Equity Equity Evaluate n 1 ply equity for resulting position End Loop Equity Equity 36 Note that evaluating the n 1 ply equity involves a cube decision since the opponent may double so GNU Backgammon will actually calculate the two n 1 ply equities a assuming no double and b assuming double take These two equities are combined with the equity for a pass and the optimum of these three is added to the resulting equity For a cubeful 2 ply evaluation GNU Backgammon will end up calculating the following cubeful 0 ply equities centered 1 cube opponent owns 2 cube owned 4 cube and opponent owns 8 cube Note that the 2 ply level does not use the cube efficiency it s not used until at the O ply level but it s possible to calculate an effective one by isolating x in the basic cube formula x eff E 2 ply cubeful E 2 ply dead E 2 ply live E 2 ply dead GNU Backgammon Manual V0 16 64 82 11 5 5 5 The cube efficiency The cube efficiency is obviously an important parameter unfortunately there haven t been much investigation carried out so GNU Backgammon basically
53. bg MWC wbg p lbg MWC Ibg For example if the w g bg distribution is 0 30 60 40 10 0 and the match score is 1 3 to 5 with the cube on 2 the cubeless MWC is MWC cubeless 30 50 30 0 30 100 10 0 0 100 0 0 45 so the cubeless MWC is 45 Evaluating the cubeful MWC is more difficult and as for the cubeful money equity it s possible to estimate cubeful MWCs from transformation on the w g bg distribution or directly calculate it from neural nets GNU Backgammon uses the former approach but the formula are currently not published 11 5 4 Normalized equity It s generally very difficult to compare MWCs For example it s hardly worth mentioning a 0 5 MWC error at DMP where as it s a huge error at 0 0 to 7 It is therefore of interesting to normalize the MWCs to some common scale The most often used normalization is Normalized Money Game Equity NEMG where the MWC for any game is transformed into the same interval as money game i e 3 to 3 due to anomalies at certain match scores the NEMG can go below 3 and above 3 The transformation is linear NEMG 2 MWC MWC 1 MWC w MWC 1 In other words extrapolation with the following two extrapolation points MWC w 1 and MWC D 1 For example suppose the score is 3 1 to 5 with the cube on 2 MWC 1 0 and MWC w 50 MWC NEMG 0 1 25 0 50 1 75 2 100 3 Note that a w g bg di
54. by choosing File Export This dialog is similar to the save dialog Again you may choose a different filename and whether to export an entire match a game or a position Then you must choose an export format as well Notice some file formats only supports export of matches and some only supports position Only when a legal combination is chosen will ending the dialog be possible The following table contains the supported file formats and the corresponding commands for export Again notice that with some formats only some of M atch G ame P osition is allowed For example to export a Jellyfish position you would issue the command export position pos lt filepath gt Encapsulated Postscript export lt P gt eps lt filepath gt HTML export lt MGP gt html lt filepath gt Jellyfish Game export lt G gt gam lt filepath gt Jellyfish Match export lt M gt mat lt filepath gt Jellyfish Position export lt P gt pos lt filepath gt LaTeX export lt MG gt latex lt filepath gt PDF export lt MG gt pdf lt filepath gt Plain Text export lt MGP gt text lt filepath gt Portable Network Graphics export lt P gt pdf lt filepath gt PostScript export lt MG gt postscript lt filepath gt Snowie Text export lt P gt snowietxt lt filepath gt 8 1 3 1 HTML export GNU Backgammon can export the current position game match or session in HTML if you wish to publish it on the web GNU Backgammon
55. ce starts with a double the sequence is skipped and the dice routine moves on to the next sequence Say an rollout as initial position is about to start using sequence 275 but that sequence begins with a double The dice routine moves to sequence 276 On the following game it will use sequence 277 it remembers how many it has already skipped GNU Backgammon Manual V0 16 43 82 So if you select rollout as initial position and 36 games then you will get a prefect set of rolls for games 1 30 and the first 6 rolls of the next perfect set the same rolls you would have gotten for games 31 36 if you d asked for 1080 games or 10800 games or 92 games or whatever The dice sequence doesn t know how many trials it will be asked for it simply generates sequences such that for a normal rollout rollout as initial position every 36 30 games you get all possible 1st rolls every 1296 1080 games get every possible first 2 rolls every 46656 38880 games you get full sets of 3 rolls etc 10 Customizing GNU Backgammon 10 1 Evaluation settings 10 1 1 Introduction to evaluation settings GNU Backgammon evaluation functionality is driven by 3 separate neural networks The neural nets evaluates each position statically and returns the outcome probabilities of the game at the given position However there are several different methods and techniques that an evaluation can use and these can be adjusted It s possible to set different levels
56. ckers Red s checkers move in the opposite direction ig White opens the game with 53 14 White rolls 64 with a checker on the bar 2 2 ee 15 White rolls 64 and bears off two checkers o 15 The dialog for starting a new match 2 2 ee 19 Click in the red rectangle to roll the dice 2 ee 20 The toolbar double buttons 2 ee 21 The hint Window is ga ee R ee RR dl RR R a ee R R 22 The cube bint Window 204 44 bs ee PRE ERR Oa RE eR A Sa Se eee R eS E 24 The tutor wind0W is s 55 25 be RRR ER RRR EERE a OE ee 25 Thetutor warming windoW ss 4 264 4 kp oy eaide eae ededrde ee Seed de Pew ei eae be 26 Click in the one of the areas marked with a red ellipse to clear the board o o 27 Click in the one of the areas marked with a red ellipse to get to the initial position 28 Clicking the White checker image will set White on turn clicking the Black image will set Black in turn 29 Click inside the red rectangle to set the dice for Black Click inside the green rectangle to set the dice for White 30 Analyze settings dialog eR RR ee 33 The Game Tecord pane ist Sek apa ae ra a AR Bae fe Bw ag Et e o 36 The Analyze pane so sore kee oA BE ee eR eek eA bat eb Paw eae ee 38 The evaluation settings dialog l a ee 45 Example of move filter settings a 47 Moye filtet La cirios bet ge be ha SESS ebb baw E ee ee ee Ga Ode wo 49 Moye filter Z
57. collection go to Gammon Links 12 1 7 Though I really read all the documentation still have questions Send an email to the GNU backgammon mailing list If it is a bug be sure to include the name of your operating system the version of gnubg you use and any error messages you receive Try to describe exactly what happens before the error occurs 12 1 8 want to make a few proposals have new ideas You re welcome Send an email with your suggestions to the GNU backgammon mailing list 12 2 How to install 12 2 1 Do I need some other software to run GNU Backgammon No Everything you need is included in the binaries If you want to use the 3D board version on Linux you might have to install the additional libraries that can be found as well on this page acepoint s directory GNU Backgammon Manual V0 16 12 2 2 want to install a newer version Go a head your settings should be saved 12 2 3 would like to compile it from the source code Good luck to you Download the source code and make sure to read one of the two following two items 12 2 4 What software do I need for compiling under GNU Linux Unpack the GNU Backgammon snapshots and follow the instructions of the file INSTALL 12 2 5 What software do need for compiling under MS Windows Follow the instructions at http www gnubg org index php itemid S0 12 2 6 It does not compile Check that you have installed all necessary development p
58. consid ered close GNU Backgammon considers a cube decision close if the relevant equities are within 0 25 from each other or if the position is too good Doubles Takes Passes The total number of doubles takes and passes in the game or match Missed doubles around DP Missed doubles around TG The number of missed doubles around the double point and too good point respectively If the equity is below 0 95 the position is considered to be around the double point else it considered to be around the too good point If you miss doubles around the double point it usually means that you double too late whereas missed doubles around the too good point means that you re too greedy and play on for gammon when the position is not too good Wrong doubles around DP Wrong doubles around TG The number of wrong doubles around the double point and too good point respectively If you have wrong doubles around the double point that generally means that you double too early where you really should hold the cube whereas wrong doubles around the too good point means that you double positions where you really should play on for a gammon or backgammon Wrong takes Wrong passes The total number of wrong takes and passes respectively Error rate total The accumulated cube errors for this game or match reported both normalized and unnormalized Error rate per cube decision The error rate per cube decision is the total error rate divided b
59. cribes a situation in the game where you probably should have doubled your opponent 12 8 4 CP From Max Friis page http xfriis dk maxfriis bg double html Cash point CP is your opponent s take point now seen from your side of the board your cash point which equals 100 minus your opponent s take point GNU Backgammon uses the term missed double below cash point which means that the player should have doubled and had he done so his opponent should take Missed double above CP in a similar way means that the correct cube action was double pass If you are the leader in the match the relevant take and double points will often look something like this where TP CP 05 100 TP rel D DP reDP TP Figure 32 The double line The double windows intervals are DP CP Your double window This window does not contain any information about redoubles but only the distance to the point where you do not want to play for the double amount of points TP DP 100 minus your opponent s double window now reTP reDP 100 minus your opponent s double window after he has taken 12 8 5 TG TG is an abbreviation for too good to double It points to a situation in the game where you probably should have kept the cube mostly because of decent sometimes very good gammon chances rather than double out your opponent GNU Backgammon Manual V0 16 78 82 12 8 6 epc See Section 12 6 8 This should be an internal li
60. ctive pip count epc pip count expected pip wastage An example 1 Position 5 checkers on the 1 point 4 checkers on the 2 point 2 Pip count 5x1 4x2 13 3 epc 2 189 expected number of remaining rolls 8 167 17 878 4 Wasted 17 878 13 4 878 It s clear hopefully that the expected pip wastage and hence the epc increases with more checkers on lower points e g you get pip wastage when rolling a 6 to bear off a checker from the 2 or 1 point It is further explained on BackGammon Galore especially in a post by Douglas Zare How do one calculate the epc then or the expected number of remaining rolls Gnu BG uses the one sided bearoff database which contains the change of bearing off the final checker in any given number of rolls A player would probably use some quite complicated heuristics please see the aforementioned post by Douglas Zare and do get back here and explain it GNU Backgammon Manual V0 16 77 82 12 7 Databases 12 7 1 What is the Database menu for Go find a newer build if you still have the database 12 8 Abbreviations 12 8 1 GWC GWC is an abbreviation for game winning chances 12 8 2 MWC MWC is an abbreviation for match winning chances 12 8 3 DP In the menu Analyze Game Match Session statistics you will see a window with some statistics Near the bottom you ll see four lines beginning with Missed and Wrong dp means doubling point and des
61. ctually gains a lot in terms of playing strength if you really need better answers than 2 ply rollouts are probably a lot better GNU Backgammon Manual V0 16 44 82 10 1 3 Defining evaluation settings First of all There are several places in GNU Backgammon where you can adjust either it s skill at playing or the quality of it s hints and analysis 10 1 4 Playing skill Settings Players Player O choose Supremo or World Class GNU Backgammon will take longer choosing its moves but they will be very strong At this setting it is much stronger than Jellyfish level 7 10 1 5 Hints Settings Evaluation choose Supremo or World Class if you want hints to be very accurate but like the playing skill setting you may find that it can take as long as 15 seconds to get an answer on a 1GHz PC Expert will be very fast but for some positions where you need to consider what your opponent may do on his roll and how you will follow it up the results will be less accurate A wild guess would be somewhere around 2 or 3 percent of the time World Class or stronger settings would give a different best move and maybe less than 1 2 percent of the time the Expert result would be seriously wrong 10 1 6 Analysis Settings Analysis these settings are used by the Analyze Move Game Match or Session command Note that this is totally different to what is used in the Hint command which uses the above settings You probably want a
62. d but not required that you contact the authors of the Document well before redistributing any large number of copies to give them a chance to provide you with an updated version of the Document GNU Backgammon Manual V0 16 80 82 F MODIFICATIONS You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above provided that you release the Modified Version under precisely this License with the Modified Version filling the role of the Document thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it In addition you must do these things in the Modified Version A Use in the Title Page and on the covers if any a title distinct from that of the Document and from those of previous versions which should if there were any be listed in the History section of the Document You may use the same title as a previous version if the original publisher of that version gives permission B List on the Title Page as authors one or more persons or entities responsible for authorship of the modifications in the Modified Version together with at least five of the principal authors of the Document all of its principal authors if it has fewer than five unless they release you from this requirement State on the Title page the name of the publisher of the Modified Version as the publisher Preserve all the copyright notices of the Document Add an ap
63. d evaluations Reduced evaluations Wo reduction sal ilo reduction al Cubeful evaluations Cubeful evaluations Cubeful chequer evaluation CubeFul chequer evaluation Noise Noise Noise 0 000 Moise 0 000 E Deterministic noise E Deterministic noise Cancel Figure 20 The evaluation settings dialog The dialog is consisting of two columns the left column is for setting the checker play decision evaluation settings and the right column is for setting the cube decision evaluation settings For each column you can select some predefined settings or you can define your own settings In the lookahead box you can adjust the lookahead of each evaluation by specifying the plies to be evaluated Each ply costs approximately a factor of 21 in computational time Also note that 2 ply is equivalent to Snowie s 3 ply setting For evaluation deeper than 0 plies it s possible to reduce the number of rolls to evaluate in the lookahead This can be set in the Reduced evaluation box Instead of averaging over all 21 possible dice rolls it is possible to average over a reduced set for example 7 rolls for the 33 speed option The 33 speed option will typically be three times faster than the full search without reduction In the box for Cubeful evaluations you can specify if you want GNU Backgammon to evaluate the cube ownership in it s evaluations With this option turned on it generally improves the evaluation spec
64. ds on where on that point you click Left mouse button black checkers and right mouse button red checkers assuming you didn t change the colors You will get used to this editing and it makes it much faster to set up a position See also Albert Silver s post on GammOnLine 8 Working with matches 8 1 Retrieving and storing backgammon files 8 1 1 The Smart Game Format GNU Backgammon uses the Smart Game Format SGF to store games matches sessions and positions SGF is used in as a standard format for several other turn based games The SGF files can store all the rolls and moves and cube decisions as well as commentary and analysis A game that uses SGF extensively is Go The format is described at this site 8 1 2 Opening and importing matches Since version 0 16 the GUI recognizes all importable files automatically with the exception of the FIBS format To open or import a file choose File Open A file dialog box will appear where you can select the file and the dialog will inform you of the recognized format if the file is importable You can also use the keyboard shortcut Ctrl O or the tool bar button labeled Open to open the file dialog box directly It is still possible to import an unrecognized file by using the underlying command line interface Enable the command pane by choosing View Command In the command pane type in import oldmoves lt filepath gt to import e g an oldmoves fibs formatted file The f
65. e front cover and Back Cover Texts on the back cover Both covers must also clearly and legibly identify you as the publisher of these copies The front cover must present the full title with all words of the title equally prominent and visible You may add other material on the covers in addition Copying with changes limited to the covers as long as they preserve the title of the Document and satisfy these conditions can be treated as verbatim copying in other respects If the required texts for either cover are too voluminous to fit legibly you should put the first ones listed as many as fit reasonably on the actual cover and continue the rest onto adjacent pages If you publish or distribute Opaque copies of the Document numbering more than 100 you must either include a machine readable Transparent copy along with each Opaque copy or state in or with each Opaque copy a computer network location from which the general network using public has access to download using public standard network protocols a complete Transparent copy of the Document free of added material If you use the latter option you must take reasonably prudent steps when you begin distribution of Opaque copies in quantity to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy directly or through your agents or retailers of that edition to the public It is requeste
66. e roll of the dice indicates how many points or pips the player is to move his checkers The checkers are always moved forward to a lower numbered point The following rules apply 1 A checker may be moved only to an open point one that is not occupied by two or more opposing checkers 2 The numbers on the two dice constitute separate moves For example if a player rolls 5 and 3 he may move one checker five spaces to an open point and another checker three spaces to an open point or he may move the one checker a total of eight spaces to an open point but only if the intermediate point either three or five spaces from the starting point is also open Figure 3 White opens the game with 53 3 A player who rolls doubles plays the numbers shown on the dice twice A roll of 6 and 6 means that the player has four sixes to use and he may move any combination of checkers he feels appropriate to complete this requirement 4 A player must use both numbers of a roll if this is legally possible or all four numbers of a double When only one number can be played the player must play that number Or if either number can be played but not both the player must play the larger one When neither number can be used the player loses his turn In the case of doubles when all four numbers cannot be played the player must play as many numbers as he can 2 4 Hitting and Entering A point occupied by a single checker of either color is called a blot
67. e the live cube take points for a 1 cube at 3 0 to 7 we need the live cube take points for the 4 cube and the 2 cube For the position above and using Woolsey s match equity table the live cube take point are Cube value TP for Black TP for White 4 0 41 2 15 38 5 1 24 5 27 3 The calculation of these are left as an exercise to the reader Ignoring backgammons the gammon rates for White and Black are 0 106 54 6 19 and 0 103 0 454 22 respectively If White wins the game his MWC will be 81 MWC 3 7 19 MWC 2 7 78 and if Black wins his MWC will be 78 MWC 4 6 22 MWC 4 5 41 If White cashes 1 point he has MWC 3 7 76 and if Black cashes he has MWC 4 6 36 Analogous to money game the live cube MWC is calculated as piecewise linear interpolation between 0 22 24 5 24 72 7 36 and 100 41 from black s point of view GNU Backgammon Manual V0 16 63 82 BWC Wins Figure 30 mptp 11 5 5 3 0 ply Cubeful equities Having established the live cube equities and MWCs we re now in position to calculate the 0 ply cubeful equities Let s start with money game the cubeless equity is 0 097 and the live cube equity can be determined from the figure above as 0 157 Thus the cubeful equity is 0 138 For the match play example at the score 3 0 the cubeless MWC is 29 1 and from the figure Black using wins 45 4 we can determine the live cu
68. er The beaver button is only activated in money game sessions where beavers are allowed y x 4 Accept Decline Beaver Figure 8 The toolbar double buttons There are also menu options from the drop down menu for all the cube actions Click Game Take from the menu to accept an offered double Ctrl T Click Game Drop from the menu to to decline an offered double Ctrl P Click Game Beaver from the menu to beaver an offered double 4 5 Resigning 4 5 1 Offering a resignation It s also possible to resign during a game To resign during play press the Resign button in the toolbar This is the button with the image of a white flag When this button is pressed a dialog box will appear where you can select if you want to resign a single game gammon or backgammon The resignation dialog may also be reached from the menu system Click Game Resign to offer your resignation GNU Backgammon Manual V0 16 22 82 4 5 2 Accepting or declining a resignation When a resignation is offered a white square will appear on the board area The square has a number 1 2 or 3 A square with a 1 means that a single game resignation is offered a 2 that a gammon resignation is offered and a 3 means that a backgammon is offered If you re using a 3D board the resignation will be a white flag instead of a square To accept the resignation click on the numbered square If you want to decline the resignation you right click instead
69. er has the left score field and player 1 the bottom player has the right score You can also set the match score in the in the match field to the right There is also a box to tick whenever the position is from a Crawford game If you want the computer to do a money game evaluation of the position you should set the match score to 0 zero GNU Backgammon Manual V0 16 31 82 7 10 Exiting Edit mode Before you can start analyzing the position you have to exit edit mode This is done by releasing the Edit button in the toolbar by clicking it Note that editing a position destroys your game record with no warning so it might be an idea to save your match if you want to keep it 7 11 Analyzing the position After you have successfully set up the position you desire you can now analyze the position You can click Hint in the toolbar to get the best move of cube decision in the same way as described in the chapter called Section 4 Hint rollouts and evaluations done from the hint window will not be saved if you try to save the position If you want to analyze the position and then be able to save the position and the analysis results you should rather do a move and then click back to the move and then choose Analyze Analyze move for the menu You can then work in the analysis pane on the right side instead of in the hint window You can enter checkers on a point by clicking on the point Notice the amount of checkers you add on a point depen
70. er 0 and 1 respectively 4 Bit 8 is the Crawford flag 1 if this game is the Crawford game 0 otherwise 5 Bit 9 11 is the game state 000 for no game started 001 for playing a game 010 if the game is over 011 if the game was resigned or 100 if the game was ended by dropping a cube 6 Bit 12 indicates whose turn it is For example suppose player 0 is on roll then bit 7 above will be 0 Player 0 now decides to double this will make bit 12 equal to 1 since it is now player 1 s turn to decide whether she takes or passes the cube 7 Bit 13 indicates whether an doubled is being offered 0 if no double is being offered and 1 if a double is being offered 8 Bit 14 15 indicates whether an resignation was offered 00 for no resignation 01 for resign of a single game 10 for resign of a gammon or 11 for resign of a backgammon The player offering the resignation is the inverse of bit 12 e g if player 0 resigns a gammon then bit 12 will be 1 as it is now player 1 now has to decide whether to accept or reject the resignation and bit 13 14 will be 10 for resign of a gammon 9 Bit 16 18 and bit 19 21 is the first and second die respectively 0 if the dice has not yet be rolled otherwise the binary encoding of the dice e g if 5 2 was rolled bit 16 21 will be 101 010 10 Bit 22 to 36 is the match length The maximum value for the match length is 32767 A match score of zero indicates that the game is a money game 11 Bit 37 51 and b
71. er Emphasis very good or bad rolls e g Alert unlucky roll The style applied to the entire table with game match and Stattable E session statistics Stattableheader The header row of the statistics table Style for the text indicating the outcome of the game or result E x match e g Jorn Thyssen wins 16 points tiny Currently unused cubedecision The style applied to the entire cube decision table cubedecisionheader Style for the header row of the cube decision table cubeequity Style for any equity or MWC in the cube decision table cubeaction Style for the text indicating the correct cube action cubeply Style for the text that states the level of evaluation cubeprobe Style for the game winning probabilities in the cube decision table corer The style applied to the entire table used for annotations or i comments e g the kibitzing from imported SGG files The style applied to the header row of the annotations commentheader table number Currently unused fontfamily Style applied to the entire body of the XHTML document Style applied to the images in the export to avoid gaps block between individual pictures both horizontally and vertically positionid Style for the Position ID and match ID GNU Backgammon Manual V0 16 70 82 12 Frequently Asked Questions 12 1 General questions 12 1 1 Whatis GNU Backgammon GNU Backgammon gnubg is a program for playing and analyzing backgammon positions games and
72. gtk module MODULES Load additional GTK modules Etc EN NES ake all warnings fatal Application Options f ANO Deano ki Do not use bearoff database C commands FILE Evaluate commands in FILE and exit d datadir DIR Read database and weight files from DIR l lang LANG Set language to LANG ISL new weights N Create new neural net of size N p python FILE Evaluate Python code in FILE and exit Bip e US Disable sound effects te EEE Do not read gnubgrc and gnubgautorc commands MOS pias Don t show gtk splash screen Ey ELY Start on tty instead of using window system v version Show version information and exit w window system only Ignore tty input when using window system display DISPLAY X display to use 4 Playing a game 4 1 Starting a new match To start a new game match or session choose File New or use the New button in the toolbar This will open a dialog box where you can select the main options for the new backgammon game you are about to begin GNU Backgammon Manual V0 16 19 82 A GNU Backgammon New Biel gt Shortcut buttons 250650008582 J Game Match Match length 7 4 Money game session Position Player settings Current player settings Manual dice A GNU Backgammon vs Human Tutor mode 2 Human vs Human Modify player settings Cancel Figure 6 The dialog for starting a new match The shortcut buttons
73. he cubeful equity for double pass is still 1 000 for the doubler The third number in figure above is the cubeful equity for the player doubling and the opponent accepting the double The different option will be listed in order with the best option highest The number right to the listed equities is the differences from the cube decision considered best The last line states the best considered cube action In the figure above GNU Backgammon considers the best cube action to be No double take When percentage number right to the proper cube action is a number which indicates the bluff potential It is the necessary percentage chance you think you can bluff your opponent into passing the cube to make the double theoretically correct This number is only available when the position is considered No double take or Too good to double pass 5 1 3 The hint tool buttons As you may see in both figures above there is a set of buttons below the move list or cube analysis Here follows a short description of what each of the buttons does 1 Eval will evaluate the selected moves or the cube decision with the current evaluation setting 2 will open the evaluation setting dialog You can then modify the evaluation setting More about evaluation settings in the next chapter 3 0 1 23 4 will evaluate the selected moves or cube decision at cubeful 0 ply or cubeful 1 ply or cubeful 2 ply and so on GNU Backgammon Manual V0 16 25 82 4 Roll
74. he section and preserve in the section all the substance and tone of each of the contributor acknowledgements and or dedications given therein L Preserve all the Invariant Sections of the Document unaltered in their text and in their titles Section numbers or the equivalent are not considered part of the section titles M Delete any section Entitled Endorsements Such a section may not be included in the Modified Version N Do not retitle any existing section to be Entitled Endorsements or to conflict in title with any Invariant Section O Preserve any Warranty Disclaimers If the Modified Version includes new front matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document you may at your option designate some or all of these sections as invariant To do this add their titles to the list of Invariant Sections in the Modified Version s license notice These titles must be distinct from any other section titles You may add a section Entitled Endorsements provided it contains nothing but endorsements of your Modified Version by various parties for example statements of peer review or that the text has been approved by an organisation as the authoritative definition of a standard You may add a passage of up to five words as a Front Cover Text and a passage of up to 25 words as a Back Cover Text to the end of the list of Cover Texts in the Modified Version Only one passage
75. he tags using the style attribute If you wish to make any modifications to the style sheet without modifying the actual source code of GNU Backgammon you have to choose one of the first two methods Note that the special export for Kit Woolsey s GammOnLine uses the third method since the XHTML is pasted into a web page without the possibility to modify the header section of the page where the style sheet is defined Thus it s not possible to modify the style of the generated XHTML for GammOnLine without modifications of the source code or extensive search and replace in the generated XHTML Below follows a description of the CSS classes used in the XHTML export Class Description movetable Style applied to the entire table used for the move analysis moveheader The header of the move analysis table movenumber The rank number of a move in the move analysis moveply The column indicating the number of plies or rollout movemove The formatted move e g 13 7 8 7 moveequity The column with the equity or MWC Special style for row that contains the actual move chosen movethemove by the player Special style for the odd rows Can be used to give an moveodd alternating color for the rows Style for the game winning probabilities and equities in the percent move analysis Emphasis blunders e g Alert missed double or Alert bad blunder move jok
76. her it s 000001 1111001 11000001 11 11000000000001 1000000011 111001 11000001 1 1 1 1000000000001 100 In little endian bytes it looks like 11100000 01110011 11110000 00000001 00110000 11100000 OxEO 0x73 OxFO 0x01 0x30 0xE0 so the 10 byte key in hex is EO 73 FO 01 30 E0 73 FO 01 30 The ID format is simply the Base64 encoding of the key Technically a Base64 encoding of 80 binary bits should consist of 14 characters followed by two padding characters but this padding is omitted in the ID format To continue the above example splitting the 10 8 bit bytes into 14 6 bit groups gives 111000 000111 001111 110000 000000 010011 000011 100000 011100 111111 000000 000001 001100 000000 In Base64 encoding these groups are respectively represented as 4HPwATDgc ABMA So the position ID of the checkers at the start of the game is simply 4HPwATDgc ABMA You can set the board in gnubg either by writing the position ID into the position text input field in the GUI or by executing the command set board 4HPwATDgc ABMA Notes 1 This encoding is obviously not as compact as it could be in particular there are lots of redundant representations of illegal positions where both players have checkers on the same point Theoretically it would be possible to get it down to 64 bits by using Walter Trice s DQ expressions but I think you d have to be a mathematical masochist to try it 2 Example code to conver
77. here with the home board on the left and the outer board on the right The points are numbered for either player starting in that player s home board The outermost point is the twenty four point which is also the opponent s one point Each player has fifteen checkers of his own color The initial arrangement of checkers is two on each player s twenty four point five on each player s thirteen point three on each player s eight point and five on each player s six point Both players have their own pair of dice and a dice cup used for shaking A double cube with the numerals 2 4 8 16 32 and 64 on its faces is used to keep track of the current stake of the game 2 2 Object of the Game The object of the game is for a player to move all of his checkers into his own home board and then bear them off The first player to bear off all of his checkers wins the game Figure 2 Direction of movement of White s checkers Red s checkers move in the opposite direction GNU Backgammon Manual V0 16 14 82 2 3 Movement of the Checkers To start the game each player throws a single die This determines both the player to go first and the numbers to be played If equal numbers come up then both players roll again until they roll different numbers The player throwing the higher number now moves his checkers according to the numbers showing on both dice After the first roll the players throw two dice and alternate turns Th
78. ially when it s close to cube decisions so we recommend that this option is turned on GNU Backgammon Manual V0 16 46 82 In the Noise box you can add noise to the evaluation This can be smart if you think the program plays to strong You can use the Noise box option to introduce noise or errors in the evaluations This is useful for introducing levels below 0 ply The lower rated bots e g GGotter on the GamesGrid backgammon server uses this technique The introduced noise can be deterministic 1 e always the same noise for the same position or it can be random 10 1 9 Predefined settings At the top of each evaluation settings column it s possible to set a predefined setting 1 Beginner This setting uses no lookahead and add up to 0 060 noise to the evaluation With this setting GNU Backgammon will evaluate like a beginner 2 Casual play This setting uses no lookahead and add up to 0 050 noise to the evaluation With this setting GNU Backgam mon will evaluate a bit better than the beginner setting but not much 3 Intermediate This setting uses no lookahead and add up to 0 030 noise to each evaluation It still plays a intermediate game 4 Advanced This setting uses no lookahead and add up to 0 015 noise to each evaluation This setting plays a good game 5 Expert This setting uses no lookahead but does not add any noise to the evaluations This settings play a strong game 6 World class This setting uses 2 ply loo
79. in the move filters you use for analysis However do note that GNU Backgammon will force evaluation at the specified ply if the actual move made is doubtful This ensures that all errors and blunders are evaluated at the same level 10 1 10 2 Defining move filters The move filter allows you to control exactly how many moves GNU is examining at each ply A ply is basically one move played by one side thus if both sides played a move it would be one whole move but two plies one for each side To change the specific settings press the Modify button Although the predefined levels such as World Class Supremo etc are tested and good you may want to know or control how GNU filters its moves to analyze and how many GNU Backgammon Manual V0 16 49 82 Hl GNU Backgammon Move filte rPredefined move Filters Large toy D ply F Enable this level Always accept 0 5 Moves K Add extra 16 E moves Sibin 20 7 1 ply Enable this level Always accept lo 3 Moves O ST ROQ extra 0 moves within OOO Figure 22 Move filter 1 If you are playing Expert level this is what GGRaccoon is set at or another 0 ply setting the Move Filter settings will not change a thing as Expert level automatically examines all moves At Supremo level this changes though as it takes a selection of the best moves from 0 ply and examines them at 2 ply This means that for those selected moves it will
80. it 52 66 is the score for player O and player 1 respectively The maximum value of the match score is 32767 For example assume the score is 2 4 in a 9 point match with player O holding a 2 cube and player 1 has just rolled 52 The match key for this will be note that the bit order is reversed below for readability 1000 00 1 0 100 1 0 00 101 010 100100000000000 010000000000000 001000000000000 In little endian the bytes looks like 01000001 10001001 00101010 00000001 00100000 00000000 00100000 00000000 00 0x41 0x89 0x2A 0x01 0x20 0x00 0x20 0x00 0x00 Analogous to the position ID from the previous section the match ID format is simply the Base64 encoding of the key To continue the example above the 9 8 bit bytes are grouped into 12 6 bits groups 010000 011000 100100 101010 000000 010010 000000 000000 001000 000000 000000 000000 In Base64 encoding the groups are represented as QYkqASAAITAAA So the match id is simply QYkqASAATAAA If someone post a match ID you can set up the position in gnubg by writing or pasting it into the Match ID text input field on the main window or by executing the command set matchid QYkqASAAIAAA GNU Backgammon Manual V0 16 69 82 11 8 Description of the CSS style sheet As mentioned above GNU Backgammon writes a CSS style sheet along with the generated XHTML file The CSS style sheet may be written verbatim in the header section of the XHTML file to an external file named gnubg css or inside t
81. ities of all position where both players have 15 or fewer checkers left on their six home board points If this file is not found GNU Backgammon will create a heuristic bearoff database for these positions This database is a also called the One Sided Database since it evaluates each player separately The other bearoff database is called gnubg_ts0 bd This bearoff database contains win probabilities for all bearoff positions with six or less checkers It also contains cubeful equities Money Game for all the positions If this file is not found at start up GNU Backgammon will evaluate late bearoff positions with the one sided bearoff database 12 3 3 Starting from the WinXP menu it plays like a beginner Open the MS Windows menu and go to the entry for gnubg Right click with the mouse and choose properties Check if the working path is the same directory as the exe file one line above If not adjust the working path 12 3 4 My screen mixes up while starting GNU Backgammon Install the newest driver for your graphic card Be sure that you have chosen at least a desktop resolution of 65535 16 bit color depth If your card is a ATI Rage somewhat there still might be some problems with the graphical interface GTK and MS Windows 12 3 5 I only get a command line interface Where is the nice board Using MS Windows just click on the correct menu entry GNU Backgammon for windows If it still doesn t work chec
82. k whether c path to your gnubg gnubg exe exists or not GNU Linux users should check if GTK is installed GNU Backgammon Manual V0 16 73 82 12 3 6 When I restart GNU Backgammon all my settings are gone Did you save your settings Settings Save settings before you quit 12 3 7 1 do not need this graphical stuff Where is the terminal for commands For GNU Linux users open a terminal and run gnubg t MS Windows users Look for a file called gnubg cli exe in GNU Backgammon s install directory or open the MS Windows menu Start Run and type c path to your gnubg gnubg cli exe There is also a menu entry GNU Backgammon Command Line Interface 12 4 Playing backgammon 12 4 1 What is the difference of a new game or match or session When you start a new match you will be asked to play to a certain amount of points for example 7 points The player who firstly reaches this amount wins the match Starting a new session means playing to an infinite amount Be aware that the rules do slightly differ mainly the Jacoby rule is applies to sessions and the Crawford to match play 12 4 2 What the heck is a beaver in Backgammon A beaver is only allowed in a money game session To beaver means to redouble retaining control of the cube immediately after your opponent doubles For more information see the glossary at Backgammon Galore 12 4 3 How do move the checkers The easiest way to move checkers is to drag a
83. kahead it uses no noise and it uses a normal move filter This plays a really strong game close to the best humans players in the world 7 Supremo This is basically the same as the World Class setting but it uses a larger move filter 8 Grandmaster This setting uses 3 ply lookahead no noises and a normal move filter This setting is extremely strong but it s also very slow 10 1 10 Move filters 10 1 10 1 Introduction to move filters GNU Backgammon uses a technique called move filters in order to prune the complete list of legal moves when analyzing checker play decisions Move filters can be considered a generalization of the search space used in earlier versions of GNU Backgammon A move filter for a given ply say 2 ply consists of four parameters for each sub ply 1 whether to analyze at all at this sub ply 2 the number of moves always accepted at the given level 3 the number of extra moves to add 4 the threshold for adding extra moves A move filter for a given ply say 2 ply consists of four parameters for each sub ply whether to analyze at all at this sub ply the number of moves always accepted at the given level the number of extra moves to add the threshold for adding extra moves For example for 2 ply checker play decisions there are two move filters one for pruning at 0 ply and another for pruning at 1 ply The predefined setting Normal has accept 0 moves and add up to 8 moves within 0 16 at 0 ply a
84. l checkers from the current position It can be regarded as a rough estimate of the raceness of the position a player with a lower pip count may in many situations want to try to race whilst the opponent with the higher pip count may want to try blocking holding See also the explanation on BackGammon Galore For the non english speaking community it might be helpful to know that when you roll a six and a five the total pips of that roll is eleven 12 6 8 What does epc mean When bearing off checkers you may notice a display showing the current epc value next to the display of Pips The epc display can be turned on or off under menu Settings gt Options gt Display at least in the current version as of June 2005 epc stands for Effective Pip Count and is an alternative measurement of the goodness of the position The usual pip count can be a misleading goodness estimate when both players are bearing off What is more important for making cubing decisions is the expected number of rolls each player needs to bear off hes checkers The effective pip count is defined as this expected number of remaining rolls multiplied with the average number of pips in a roll which is 8 167 The average number of pips in a roll would be 7 if rolling a double wouldn t yield a double pip count i e a double 6 yields 24 pips not 12 Thus epc takes into account not only the current pip count but also the expected pip wastage 1 effe
85. ll mark moves very bad bad etc based on the threshold you ve defined in the analysis settings GNU Backgammon can currently not automatically mark moves e g good but you can mark moves good yourself 4 Error rate total The first number is the total amount of normalized equity that the player gave up during this game or match The number in parenthesis is the un normalized counterpart for money play the all errors are multiplied with the value of the cube and for match play the total match winning chance given up by the player is reported 5 Error rate per move The error rate per move is the total error rate divided by the number of unforced moves Note that 1s different from Snowie 4 that defines the error rate per move as the total error rate divided by the total number of moves for both players i e the sum of total moves for both players In general your error rate per move will be lower in Snowie than in GNU Backgammon 6 Checker play rating GNU Backgammon will assign a rating for your checker play ranging from Awful to Supernatural See the description for the overall rating below 8 4 3 2 Luck analysis This section provides information about how Ms Fortuna distributed her luck The following information is available 1 Rolls marked xxx The number of moves marked very lucky lucky etc Moves marked very lucky are huge jokers that improve your equity with more the 0 6 relative to the average equity GNU Backgammon nor
86. lor You can also hit opponent blots with the drag and drop edit method This method of editing comes handy when there is just a small adjustment to be done in the position GNU Backgammon Manual V0 16 29 82 7 6 Setting the player on turn The player on turn can be set by clicking the small checker icons below the board See figure below Score 5 oway Score 0 S aueay the Figure 15 Clicking the White checker image will set White on turn clicking the Black image will set Black in turn Note that setting the turn sets the turn before the dice has been rolled If there is a dice present at the board setting the turn will remove the dice rolled In this way you can set up a position to be a cube decision evaluation instead of a move decision evaluation The turn can also be set by choosing Game Set turn Both these methods for setting the player on turn can also be used without being in edit mode 7 7 Setting the dice You can set the dice for a player by clicking in the middle part of the board where you usually click when you roll the dice while playing Click in the middle of the right playing area to set the dice for player 0 the bottom player Click the left dice rolling area to set the dice for player 1 the top player Once you click one of these areas the dice selection widget will appear and you can select a dice roll by clicking on a dice pair GNU Backgammon Manual V0 1
87. luations 10 1 12 Reduced evaluations This option is designed to increase the speed of play by taking a shortcut Instead of averaging over all 21 possible dice rolls it is possible to average over a reduced set such as only 7 rolls which would be 1 3 or 33 The 33 speed option should be approximately 3 times faster than the full search with no reduction One point it has been noted that this can badly hurt GNU Backgammon s checker play so it is not advised to use it here 10 1 13 Pruning neural networks A new feature in the evaluation is the use of a set of neural networks just to prune away move candidates within a deeper ply search This increases the speed considerably and it doesn t lose much playing strength compared to evaluation without these pruning neural nets Jim Segrave has just done an analysis of this and found that less than 1 of all moves come out different with the pruning nets activated In most of these positions the move would not have made any difference to the game at all Notice You can not use both reduced evaluations and pruning neural nets GNU Backgammon Manual V0 16 53 82 10 1 14 Noise If you think GNU Backgammon plays too strong for you you can add some noise to its evaluation The number you add into the field in the evaluations setting is the limit amount of noise that will be added to the evaluation If noise is added to the evaluations GNU Backgammon will take a Box Miller transform of a point
88. ly evaluation of Snowie It s possible that Snowie s is a playing ply while gnubg s is a position evaluation ply When playing at 1 ply Snowie will make each possible move for the player s roll that s 1 ply and analyze the resulting positions Playing at 2 ply it will take each of those positions and make all the opponent moves for all possible rolls the 2nd ply and then analyze the resulting positions In GNU Backgammon the initial set of possible moves is taken for granted i e not counted as a ply because gnubg s plies are position evaluation plies Thus for each of those possible moves a 0 ply analysis is done gnubg s discounting of the first set of moves perhaps makes the counting seem funny Looking at it a different way if you give GNU Backgammon a position and analyze it at 1 ply it will make all the moves for all possible rolls the 1st ply and then analyze the resulting positions With Snowie it will assume that the position arose from a move that s a pretend 1st ply then make all the moves for all possible rolls the 2nd ply and analyze them This time it s Snowie that seems to be counting strangely 12 5 5 What is noise Noise is a facility for disturbing GNU Backgammon s 0 ply evaluation Raising the noise level decreases its playing strength 12 5 6 What is reduced evaluation Reduced searches only work with 2 ply evaluations and deeper It cuts the search for candidate moves to increase evaluation speed
89. mally uses cubeful 0 ply evaluations to calculate the luck but you can change that under the analysis settings See below for a complete overview of what is considered very lucky lucky etc 2 Luck rate total The total luck for this game or match reported both normalized and unnormalized 3 Luck rate per move The luck rate per move reported both normalized and unnormalized 4 Luck rating Based on the luck rate per move GNU Backgammon will assign you a humorous luck rating See below for the possible ratings Thresholds for marking of rolls Deviation of equity from average Roll is marked gt 0 6 very lucky 0 3 0 6 lucky 0 3 0 3 unmarked 0 6 0 3 unlucky lt 0 6 very unlucky Luck ratings GNU Backgammon Manual V0 16 40 82 Normalized luck rate per move Luck rating gt 0 10 Cheater 0 06 0 10 Go to Las Vegas immediately 0 02 0 06 Good dice man 0 02 0 02 none 0 06 0 02 Better luck next time 0 06 0 10 Go to bed lt 0 10 Haaa haaa 8 4 3 3 Cube statistics This section provides a summary of the cube decision statistics the number of cube decisions missed doubles etc 1 2 Total cube decisions The total number of cube decisions i e the sum of no doubles doubles takes and passes Close or actual cube decisions Similar to Total cube decisions except that no doubles are only included if they re
90. matches It s based on a neural network You may play GNU Backgammon using the command line or a graphical interface based on GTK 12 1 2 What operating systems are supported Currently GNU Backgammon is actually designed for GNU Linux It also compiles and hopefully runs under BSD IRIX Solaris and True64 Unix Last but not least there are frequently binaries for MS Windows It has also been ported to MacOS When you successfully port GNU Backgammon to other operating systems you are welcome to give us a note at the GNU backgammon mailing list 12 1 3 Where do get it The official website is http www gnubg org Binaries and source code for GNU Backgammon can be downloaded from this site Up to date source code can be accessed through CVS 12 1 4 What do I have to pay for GNU Backgammon GNU Backgammon is Free Software and is a part of the GNU Project You may download it for free For more information see the GNU General Public License But be aware that GNU Backgammon is not public domain software or shareware as you perhaps know from MS Windows GNU Backgammon is free as in freedom i e all the source code is there for you to inspect change or distribute as long as you keep said license 12 1 5 This GNU stuff sounds interesting Take a look at the GNU home page It s also the page for Free Software Foundation 12 1 6 I want to learn more about backgammon A good place to start is Backgammon Galore For an extensive link
91. mers o a RA an bed waa eS AA AS a OG k 13 2 3 Movementor the Checkers s isane bag See ds A E ee bet aed een NEH SE OR 14 24 Hitting and Entering 2 eins SERA RR RE ee eee AR aa A a a a OE Se a 14 2 3 Bearno OW s r poi s soe p ee Se ee EES EERE SRE A RE ERE eae hoa le 15 2 6 DOUDUDME isa a UA aoe a Ae AGO AA RE ae Ae meee e 16 2 7 Gammons and Backgammons 2 2 00 ee 16 28 Optional R les songe saoe e eee kee REY Gee bE wR Oe SRE EA See eee ee RG Se 16 29 Rules tor Match Play sir 4s Ore op RP RA Er de da 16 3 Starting GNU Backgammon 17 3 1 Eat and UNIX cuna a eA ew a Ba Ge eA Goa leo aoe ao amp ak 17 3 2 Microsoft Windows s o e sa soca koe epo a RRR a a ee e e 17 33 Mac OS on A E EIN ae E ne a Ge Si Ge ee AEE Ea 17 34 Command line options lt seces epe A ee RA KR ERR EK E RE ce ONE Boe eee e I7 4 Playing a game 18 4 J Starine a new match 6 5 ii E ae a eatin BS ee A BES ELD OS e 18 42 Rolling the dice rais ea os he he WS Ee Ee RRO AAA AAA See LSE SGA 19 4 3 Moving the Checkers e viv kus Gnd orb eS ES Ee we RES ee Be EE ESS Se See Se Eo Se o 20 4 3 1 Moving by drag and drop 20 4 3 2 Moving checkers by clicking oe e ee ee 20 4 3 3 UndO MOVE 22 amp eek e a eS RA ee ee a a ee eb 21 4 3 4 Some shoricutS 24 25 4235 5844044 Aes eka Ree a Sa eB ee 21 44 Using the double cube s g eces agresia en ROY RS ORR EH Ok eas oe PRESSE ES SS 21 441 Oftermpra double p dori e eee ke Pee ee RAR oe ee Re a ad 21 4
92. mmon is supplied with a program makebearoff that is used to generate bearoff databases Due to various limitations it is only possible to generate bearoff databases with a size less than 2GB i e the 13pt one sided database and the 11 checker two sided database are the largest databases that can be generated with makebearoff To generate one sided database issue makebearoff o 10 f gnubg_os bd to generate the one sided 10 point database The program makebearoff uses a cache to store previously generated positions You may set the cache size with the s size option e g makebearoff o 10 s 123456789 f gnubg_os bd to use 123 456 789 bytes of memory for cache size In general if the cache size is less than the size of the database to be generated then extra time is needed to generate the bearoff database because some positions may have to be calculated several times makebearoff can also reuse previously generated databases so if you already had generated the 9 point database you can reuse it mv gnubg_os bd gnubg_os9 bd makebearoff o 10 O gnubg_os9 bd f gnubg_os bd Note that makebearoff requires temporary disk space to generate both one sided and two sided databases In general twice the disk space of the database to be generated is needed To generate a two sided database issue makebearoff t 6x8 f gnubg_ts bd This example will generate the 8 checkers on 6 points database Again it s possible to adjust the amount of memory wi
93. n Secondary Sections whose titles are designated as being those of Invariant Sections in the notice that says that the Document is released under this License If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant The Document may contain zero Invariant Sections If the Document does not identify any Invariant Sections then there are none The Cover Texts are certain short passages of text that are listed as Front Cover Texts or Back Cover Texts in the notice that says that the Document is released under this License A Front Cover Text may be at most 5 words and a Back Cover Text may be at most 25 words A Transparent copy of the Document means a machine readable copy represented in a format whose specification is available to the general public that is suitable for revising the document straightforwardly with generic text editors or for images composed of pixels generic paint programs or for drawings some widely available drawing editor and that is suitable for input to text GNU Backgammon Manual V0 16 79 82 formatters or for automatic translation to a variety of formats suitable for input to text formatters A copy made in an otherwise Transparent file format whose markup or absence of markup has been arranged to thwart or discourage subsequent modification by readers is not Transparent An image format is not Transparent if used for any substantial amount of text A copy
94. nd drop Put your mouse pointer over a checker you want to move press the left mouse button and drag the checker to the desired point holding down the button while dragging If you prefer to use mouse clicks the left mouse button is for the left die shown on your board Right click your mouse for the right die If you always want the higher number displayed on the left go to the menu Settings Appearance General and select Show higher die on left 12 4 4 Why am I allowed to place more than 5 checkers on a point The official backgammon tournament rules allow to put all 15 checkers on a point If you want to play with a maximum of 5 checkers go to the menu Settings and activate the Egyptian Rule Notice the Egyptian Rule is not in the standard rules of backgammon The position evaluator in GNU Backgammon doesn t have a clue about how to evaluate positions according to the Egyptian rule either It strongly recommended that this rule is not used if you re trying to learn backgammon 12 4 5 GNU Backgammon plays poorly Are you sure If the answer is yes you should think about going to Monte Carlo this summer and win the Backgammon World Championship If this plan fails check whether the weights file is loaded at start up See also Section 12 3 2 12 4 6 GNU Backgammon is too strong for me Go to the menu Settings Players and change the values for Player 0 There is also a set of predefined settings you may choose from G
95. nd no pruning at 1 ply Consider the opening position where 4 2 has been rolled GNU Backgammon Manual V0 16 47 82 13 20 21 22 23 M Figure 21 Example of move filter settings GNU Backgammon starts by finding all possible moves and evaluate those at 0 ply 1 Cubeful 0 ply 8 4 6 4 Eq 0 189 2 Cubeful 0 ply 24 20 13 11 Eq 0 046 0 143 3 Cubeful 0 ply 13 11 13 9 Eq 0 044 0 145 4 Cubeful 0 ply 24 22 13 9 Eq 0 034 0 155 5 Cubeful 0 ply 24 22 24 20 Eq 0 006 0 194 6 Cubeful 0 ply 24 18 Eq 0 009 0 198 Te Cubeful 0 ply 24 20 6 4 Eq 0 019 0 208 8 Cubeful 0 ply 13 9 6 4 Eq 0 024 0 213 9 Cubeful 0 ply 13 7 Eq 0 052 0 241 10 Cubeful 0 ply 24 20 8 6 Eq 0 053 0 242 According to the move filter the first 0 moves are accepted The equity of the best move is 0 189 and according to the move filter we add up to 8 extra moves if they re within 0 160 that is if they have equity higher than 0 029 Moves 5 through 18 all have equity lower that so the move list after pruning at 0 ply consists of moves 1 through 4 According to the move filter we do not perform any pruning at 1 ply so moves 1 through 4 are submitted for evaluation at 2 ply 1 Cubeful 2 ply 8 4 6 4 Eq 0 180 2 Cubeful 2 ply 24 20 13 11 Eq 0 052 0 127 3 Cubeful 2 ply 13 11 13 9 Eq 0 043 0 137 4 Cubeful 2 ply 24 22 13 9 Eq
96. nk not an external one But I can t figure out how to link internally to a subsection Anyone A GNU Free Documentation License Copyright C 2000 2001 2002 Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed B PREAMBLE The purpose of this License is to make a manual textbook or other functional and useful document free in the sense of freedom to assure everyone the effective freedom to copy and redistribute it with or without modifying it either commercially or noncommercially Secondarily this License preserves for the author and publisher a way to get credit for their work while not being considered responsible for modifications made by others This License is a kind of copyleft which means that derivative works of the document must themselves be free in the same sense It complements the GNU General Public License which is a copyleft license designed for free software We have designed this License in order to use it for manuals for free software because free software needs free documentation a free program should come with manuals providing the same freedoms that the software does But this License is not limited to software manuals it can be used for any textual work regardless of subject matter or whether it is published as a printed book We recommend this License princip
97. nts To use this License in a document you have written include a copy of the License in the document and put the following copyright and license notices just after the title page Copyright c YEAR YOUR NAME Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation with no Invariant Sections no Front Cover Texts and no Back Cover Texts A copy of the license is included in the section entitled GNU Free Documentation License If you have Invariant Sections Front Cover Texts and Back Cover Texts replace the with Texts line with this with the Invariant Sections being LIST THEIR TITLES with the Front Cover Texts being LIST and with the Back Cover Texts being LIST If you have Invariant Sections without Cover Texts or some other combination of the three merge those two alternatives to suit the situation If your document contains nontrivial examples of program code we recommend releasing these examples in parallel under your choice of free software license such as the GNU General Public License to permit their use in free software
98. number of points that were at stake prior to the redouble Otherwise he becomes the new owner of the cube and the game continues at twice the previous stakes There is no limit to the number of redoubles in a game 2 7 Gammons and Backgammons At the end of the game if the losing player has borne off at least one checker he loses only the value showing on the double cube one point if there have been no doubles However if the loser has not borne off any of his checkers he is gammoned and loses twice the value of the double cube Or worse if the loser has not borne off any of his checkers and still has a checker on the bar or in the winner s home board he is backgammoned and loses three times the value of the double cube 2 8 Optional Rules The following optional rules are in widespread use 1 Automatic doubles If identical numbers are thrown on the first roll the stakes are doubled The double cube is turned to 2 and remains in the middle Players usually agree to limit the number of automatic doubles to one per game 2 Beavers When a player is doubled he may immediately redouble beaver while retaining possession of the cube The original doubler has the option of accepting or refusing as with a normal double 3 The Jacoby Rule Gammons and backgammons count only as a single game if neither player has offered a double during the course of the game This rule speeds up play by eliminating situations where a player avoids doubling
99. o count the googol balls we just give the urn a really good shake and then pull 100 balls out without looking and say for instance Well I got 53 wins 31 losses 9 gammon wins 6 gammon losses and a backgammon win looks like my equity s roughly 0 26 and go home If we were a bit more thorough we could go a bit further and figure out that by cheating and measuring the sample proportions instead of the population proportions we introduced a standard error of 0 06 into our result Of course the trick is to select a sample size that s big enough that you reduce the standard error to a tolerable level but small enough that the answer arrives before you get bored It will come as no surprise that a rollout with a limited number of trials follows exactly the same procedure It s sufficient to say that the proportion of wins gammons etc that come up when GNU Backgammon plays against itself say 1296 times aren t likely to vary all that much from the proportion we would get if we measured the proportion of results in every game we could possibly get of GNU Backgammon playing against itself Of course there may still be some doubt whether the results of GNU Backgammon vs GNU Backgammon are representative of the results of a perfect player vs a perfect player or of you vs Joe Average but that s another story GNU Backgammon Manual V0 16 42 82 9 2 Rollouts in GNU Backgammon In GNU Backgammon the Rollout function implements
100. of Front Cover Text and one of Back Cover Text may GNU Backgammon Manual V0 16 81 82 be added by or through arrangements made by any one entity If the Document already includes a cover text for the same cover previously added by you or by arrangement made by the same entity you are acting on behalf of you may not add another but you may replace the old one on explicit permission from the previous publisher that added the old one The author s and publisher s of the Document do not by this License give permission to use their names for publicity for orto assert or imply endorsement of any Modified Version G COMBINING DOCUMENTS You may combine the Document with other documents released under this License under the terms defined in section 4 above for modified versions provided that you include in the combination all of the Invariant Sections of all of the original documents unmodified and list them all as Invariant Sections of your combined work in its license notice and that you preserve all their Warranty Disclaimers The combined work need only contain one copy of this License and multiple identical Invariant Sections may be replaced with a single copy If there are multiple Invariant Sections with the same name but different contents make the title of each such section unique by adding at the end of it in parentheses the name of the original author or publisher of that section if known or else a unique number Make the same
101. of a cube play meaning it was turned select the Take Pass decision to enter the commentary The reason is that if you export it after and didn t do this the commentary appears before the cube decision and not after as it should Tip while entering the match if you wish to see GNU Backgammon s opinion while you are entering the moves play the move on the board and press the Hint button in the tool bar In the latest builds if you have done this the results will then be placed with the move so that it means it is already analyzed when you run the full match analysis Mind you it will preserve the information even if you ran a deeper 3 ply or 4 ply from the Hint window After playing the move and confirming the dice go back in the move list and click on the move and you ll see the analysis appear in the Analysis pane as it should GNU Backgammon Manual V0 16 34 82 8 2 1 Entering illegal moves It s possible to enter illegal moves with a little trick This is a step by step guide for the example If a player rolls 41 and the player makes an illegal move as the dice showed 31 1 Manually enter the roll which was rolled 41 2 Do a legal move with 41 this is just to get the analysis of the roll and the best legal move 3 Click the dice to pick them up and complete the move 4 Now before you roll the opponents dice click the Edit button 5 While holding down the CTRL button on your keyboard you can now drag the checker
102. of lookahead it s possible to add noise to the evaluation and each evaluation can be done cubeful or cubeless All these setting together form a total evaluation setting In GNU Backgammon there are several of these evaluations setting for each operation GNU Backgammon does 1 Evaluation setting for Hints and Evaluations 2 Evaluation setting for analysis 3 Evaluation setting for GNU Backgammon when it s playing 4 Several evaluation settings for each move performed in a rollout 10 1 2 The depth to search and plies A ply is simply considered to be one turn by a player Any position can be evaluated at 0 ply That means that GNU Backgammon does not look ahead in the game to evaluate the position When GNU Backgammon is evaluating a checker play decision 1t looks at all resulting positions after all the legal moves with the given dice roll and evaluates these position at the given ply It s possible to set the search depth by specifying the plies lookahead in any evaluation settings dialog Snowie users GNU Backgammon differs from some other software notably Snowie in that GNU Backgammon zero ply is the same as Snowie 1 ply In the same way what is called 2 ply in GNU Backgammon will therefore be similar to a Snowie 3 ply For GNU Backgammon a 0 ply evaluation of a move would be done by Build a list of all legal moves For each move take the resulting board position and use the neural net to estimate the ex pected percentage of
103. ollowing table contains the supported formats and the corresponding commands for manual import of a file FIBS oldmoves format import oldmoves lt filepath gt Gamesgrid Save Game import sgg lt filepath gt GammonEmpire Game import empire lt filepath gt Hans Berliner s BKG Format import bkg lt filepath gt Jellyfish Game import gam lt filepath gt Jellyfish Match import mat lt filepath gt Jellyfish Position import pos lt filepath gt PartyGammon Game import party lt filepath gt Snowie Text import snowietxt lt filepath gt True Moneygames import tmg lt filepath gt GNU Backgammon Manual V0 16 32 82 8 1 3 Saving and exporting positions games or matches If you have played or imported a match into GNU Backgammon and wish to save your efforts you can choose File Save A file dialog box will appear and you can type in a file name or keep the suggested default file name The suggested default file name contains the date the players name and the length of the match This will save the whole match of the current match or session If there is any analysis or commentary available this will also be saved to the file You can also use the tool bar button labeled Save to open the file dialog box directly There is also a keyboard shortcut Ctrl S for saving a match or session O Warning Please note that saving a position will not save any analysis The export dialog is accessed
104. om the six point If there is no checker on the point indicated by the roll the player must make a legal move using a checker on a higher numbered point If there are no checkers on higher numbered points the player is permitted and required to remove a checker from the highest point on which one of his checkers resides A player is under no obligation to bear off if he can make an otherwise legal move Figure 5 White rolls 64 and bears off two checkers A player must have all of his active checkers in his home board in order to bear off If a checker is hit during the bear off process the player must bring that checker back to his home board before continuing to bear off The first player to bear off all fifteen checkers wins the game GNU Backgammon Manual V0 16 16 82 2 6 Doubling Backgammon is played for an agreed stake per point Each game starts at one point During the course of the game a player who feels he has a sufficient advantage may propose doubling the stakes He may do this only at the start of his own turn and before he has rolled the dice A player who is offered a double may refuse in which case he concedes the game and pays one point Otherwise he must accept the double and play on for the new higher stakes A player who accepts a double becomes the owner of the cube and only he may make the next double Subsequent doubles in the same game are called redoubles If a player refuses a redouble he must pay the
105. out will start a rollout A rollout is simply a Monte Carlo simulation of a backgammon position More about rollouts in a later chapter of the selected moves or cube decision 5 will open the rollout settings dialog This dialog will be further described later in this manual 6 MWC Match Winning Chance If this button is pressed the values in the hint window will be shown as the chance to win the whole match If this button is unpressed or there is a money game that s played the values in the hint window is reported as Equity Notice The equity in a match is actually a recalculation from match winning chance to equity This recalculated number is often referred to as EMG Equivalent to Money Game The EMG number is comparable to the equity in a money game and are therefore labeled Equity 7 Show will show the board as it would be after the selected move is made The button is only available in the checker play hint window 8 Move will make the move selected in the list It s also possible to make a move directly from the list by double clicking on the move The button is also available only in the checker play hint window 9 Copy will copy the text of all selected moves to clipboard 10 Temp Map will show Sho Sengoku s temperature map This map is further described later in the document When this window remembers its size and position it will really become useful 5 2 Tutor mode One of the greatest tools for lea
106. pay for GNU Backgammon 2 0 0 0 00000000004 70 12 1 5 This GNU stuff sounds interesting 2 2 20 00000002 a 70 12 1 6 I want to learn more about backgammon 0 00 0 eee ee 70 12 1 7 Though I really read all the documentation I still have questions o o 70 12 1 8 I want to make a few proposals I have new ideas 2 2 0 0000002 eee ee 70 12 2 Howto install Vis do cr oe RP EE ee A ES SE kee de de 70 12 2 1 Do I need some other software to run GNU Backgammon o o e 70 12 2 2 I want to install a newer Version 71 12 2 3 I would like to compile it from the source code o o ee 71 12 2 4 What software do I need for compiling under GNU Linux 2 2 en 71 12 2 5 What software do I need for compiling under MS Windows o o 71 12 2 6 Itdoes mot eompile 2 2 0 2 000002 ee 71 12 2 7 On what CPU will GNU Backgammon run fastest o e e e e 71 12 3 Running GNU Backgammon 72 12 3 1 I get an error message when Starting 72 12 3 2 GNU Backgammon complains about missing files o a 12 12 3 3 Starting from the WinXP menu it plays like a beginner o ee ee T2 12 3 4 My screen mixes up while starting GNU Backgammon a 72 12 3 5 I only get a command line interface Where is the nice board T2 12 3 6 When I restart GNU Backgammon all my settings are gone o oo ee ee ee 73 GNU Backgammon Manual V0 1
107. propriate copyright notice for your modifications adjacent to the other copyright notices m mo O Include immediately after the copyright notices a license notice giving the public permission to use the Modified Version under the terms of this License in the form shown in the section Addendum below G Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document s license notice H Include an unaltered copy of this License I Preserve the section Entitled History Preserve its Title and add to it an item stating at least the title year new authors and publisher of the Modified Version as given on the Title Page If there is no section Entitled History in the Document create one stating the title year authors and publisher of the Document as given on its Title Page then add an item describing the Modified Version as stated in the previous sentence J Preserve the network location if any given in the Document for public access to a Transparent copy of the Document and likewise the network locations given in the Document for previous versions it was based on These may be placed in the History section You may omit a network location for a work that was published at least four years before the Document itself or if the original publisher of the version it refers to gives permission K For any section Entitled Acknowledgements or Dedications Preserve the Title of t
108. quities For a double decision GNU Backgam mon calculates the cubeful equity for no double and the cubeful equity for double take Combined with the equity for double pass it s possible to determine the correct cube action The figure below shows the relevant cubeful equities for White and black s cube decisions in sample position from earlier 25 Equity m Wire Figure 31 mgcd GNU Backgammon Manual V0 16 65 82 On 0 ply Black will double when the green curve White owns 2 cube is above the red curve centered cube and White will take as long as the green curve is below 1 Similarly White will double when the blue curve Black owns 2 cube is below the red curve centered cube and Black takes as long as the blue curve is above 1 Note that GNU Backgammon doesn t calculate the take point or double point explicitly The cube decision is simply made by comparing equities from the figure 11 5 5 7 Beyond the simple model Janowski has developed two other models for cubeful equities The first is a generalization of the one used by GNU Backgammon it introduces two cube efficiencies instead of one Often you may see that the cube efficiencies are different for the two players and the refined general model as it is named by Janowski tries to take this into consideration by using different cube efficiency parameters for the two players For example the blitzer may have another cube efficiency that the blitzee The
109. r a GTK interface with a graphical board window Both 2D and 3D graphics are available e Tournament match and money session cube handling and cubeful play All governed by an underlying cubeless money game based neuralnet e Support for both 1 sided and 2 sided bearoff databases 1 sided bearoff database for 15 checkers on the first 6 points and optional 2 sided database kept in memory Optional larger 1 sided and 2 sided databases stored on disk GNU Backgammon Manual V0 16 12 82 e Automated rollouts of positions with lookahead and race variance reduction where appropriate Rollouts may be extended e Automatic and manual annotation analysis and commentary of games and matches e Record keeping of statistics of players in games and matches both native inside GNU Backgammon and externally using relational databases and Python e Loading and saving analyzed games and matches as sgf files Smart Game Format e Exporting positions games and matches to eps Encapsulated Postscript gam Jellyfish Game html HTML mat Jelly fish Match pdf PDF png Portable Network Graphics pos Jellyfish Position ps PostScript sgf Gnu Backgammon File tex LaTeX txt Plain Text txt Snowie Text e Import of matches and positions from a number of file formats bkg Hans Berliner s BKG Format gam GammonEmpire Game gam PartyGammon Game mat Jellyfish Match pos Jellyfish Position sgf Gnu Backgammon
110. re 25 Cubeful example In this position black has rolled 51 and he has a good position If the position is evaluated cubeless the best move is 13 7 Black can hope white does not roll 34 or 35 form the bar and has now a good chance to close white out in the next few rolls However if white rolls one of the four hitting numbers from the bar white will quite soon have a really hot redouble This redouble increases whites equity so much that black actually should play this move safe He should play 13 8 6 5 However if the evaluation was set to cubeless an setting which assumes white will never redouble black should play 13 8 Here s another example GNU Backgammon Manual V0 16 52 82 Figure 26 Cubeful example 2 This is from a 5 point match where black has 1 point and white has 3 points Black wins the opening roll and considers playing 13 11 6 5 or 24 23 13 11 If GNU Backgammon uses a cubeless evaluation it will play 24 23 13 11 But if you re using a cubeful evaluation it will play 13 11 6 5 Slotting with 6 5 is at this score a better move even though it loses more gammons The gammons black are losing won t matter anyway since black will turn the cube in the next few rolls anyway The slotting play also wins more gammons and with the cube tuned to 2 black should play towards gammonish positions at this score You can read more about cubeful evaluations in the Appendix It s recommended that you use cubeful checker eva
111. rification of databases To verify that your generated or downloaded bearoff database is correct the table below lists the MD5 checksums for a number of possible databases 11 1 4 One sided bearoff databases compressed The table below contains the MDS checksums for the compressed one sided bearoff databases i e databases generated with default options Checkers Points MD5 checksum 15 1 c789f049ec98ce4e307b471257999f39 15 2 b6e61c1625ae4b3b164e93ab064192b9 15 3 346dae6139ccb4b227c534373e5c52e4 15 4 65325515f9f22fd50277f7ff25b2a343 15 5 2064f9a56b23117d053a573c96a92fa2 15 6 3dc7b833c4670849cee00479a9e21b49 15 7 67235c8e0ee152df5daf36cbeaeSb3c2 15 8 a4acbb5c7e9el f08e561 afeOaf934e5c 15 9 O9c4ddab4e51c3e668c9c97b8f8768dbc 15 10 81b3898f06bbd08ee8295a83925 1al0a 15 11 78ecb4be86dab6af8755ea4063d50fb6 15 12 770fcff48894a96ebb2249343ef94866 15 13 cc74b69a62f6e648936f533838a527a8 15 14 not available 15 15 not available 15 16 not available 15 17 not available 15 18 not available 11 1 5 Two sided bearoff databases with cubeless and cubeful equities The table below contains the MD5 checksums for the default two sided bearoff databases Checkers Points MD5 checksum 1 6 Ted6f8e7fce 1 6ea2b80e07a4a5 16653c 2 6 e9d760bf213841c285245ed757a52f4d 3 6 9d67da3db32ad4720cc38eecf9a67967 4 6 9156f37032d1d4b0352a4 1 186e632dfc 5 6
112. rning is Tutor Mode Tutor mode can be activated by clicking Settings Options and then click on the Tutor flag Activate Tutor Mode by checking the Tutor mode check box Tutor mode F Cube Decisions F Chequer play Tutor decisions p 7 Same as Evaluation Same as Analysis Warning level Bad Figure 11 The tutor window In Tutor Mode GNU Backgammon will analyze your moves and or cube decisions and compare them with its choices You set the threshold for its alerts for example if you set it for bad then it will only warn you when you make a bad mistake It will then allow you to re examine your choice go right ahead with it or provide a hint essentially showing you its analysis The tutor can give warnings on both cube decisions and checker play If you want the tutor to only warn on cube decisions you can uncheck the box for the Checker play Likewise if you want it to only warn on checker play decisions you can uncheck the box for the Cube decisions GNU Backgammon Manual V0 16 26 82 SS GNU Backgammon Tutor Joe You may be about to make a doubtful play Are you sure Play Anyway Rethink End Tutor Mode Figure 12 The tutor warning window In the above figure you can see a warning dialog from the tutor mode If you press the button labeled Play anyway the move you made will be kept and the game will continue If you press the Rethink button the dialog will close and the checker
113. ry the requirement section 4 to Preserve 1ts Title section 1 will typically require changing the actual title K TERMINATION You may not copy modify sublicense or distribute the Document except as expressly provided for under this License Any other attempt to copy modify sublicense or distribute the Document is void and will automatically terminate your rights under this License However parties who have received copies or rights from you under this License will not have their licenses terminated so long as such parties remain in full compliance L FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new revised versions of the GNU Free Documentation License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns See http www gnu org copyleft Each version of the License is given a distinguishing version number If the Document specifies that a particular numbered version of this License or any later version applies to it you have the option of following the terms and conditions either of that specified version or of any later version that has been published not as a draft by the Free Software Foundation If the Document does not specify a version number of this License you may choose any version ever published not as a draft by the Free Software Foundation M ADDENDUM How to use this License for your docume
114. s of the different outcomes you can click on the button labeled Details This will then show you a list with these numbers The other page of the notebook is the cube decision analysis This analysis show exactly the same as in the Hint window described in the chapter called Playing a game or match Note that the cube decision page will only be available if there is a cube decision It will not be visible if the cube is not available to the player There is also a set of tool buttons in the analysis panel These buttons does exactly the same as the tool buttons in the Hint window which is described in the the chapter called Playing a game or match GNU Backgammon Manual V0 16 39 82 8 4 3 Statistics You can get a summary of the analysis from the game match or session analysis The game analysis is a summary for the current game whereas the match or session statistics is a summary of all the games in the match or session The match analysis is available in the GUI from Analyze Match Statistics or at the bottom of exported files 8 4 3 1 Checker play statistics This section provides a summary of the checker play statistics The following information is available 1 Total moves The total number of moves in the match 2 Unforced moves The number of unforced moves i e all checker play decisions which had more than one legal move 3 Moves marked xxx The number of moves marked very good very bad etc The analysis wi
115. s that you moved will be returned to their original positions You can then rethink the position and try an alternative move Keep doing this until the Tutor accepts your move as being good enough Alternatively you can press the Hint button to show the hint window with its list of possible moves and their evaluations Finally if you press the End Tutor Mode button the dialog will close and turn Tutor Mode off A similar warning window will also appear for poor cube handling 6 Time controls The time control feature is not fully implemented with the user interface yet Hopefully this will be improved in the future 7 Setting up a position Think about the Friday night chouette where there was this tough choice between two move candidates Which move was the best Or what about that match score cube decision from the weekend tournament Wouldn t it be nice to be able to set up the position in GNU Backgammon and ask for it s opinion This is possible in GNU Backgammon and it s one of the features that really can give you the answer to a lot of questions and in that way give you a better understanding of the game 7 1 Entering Edit mode To set up a position you have to be in Edit mode To enter Edit mode you simply click the Edit button in the tool bar There is currently no keyboard shortcut or menu item for entering edit mode The Edit button is a toggle button and you will stay in edit mode until you release the button by clicking it ag
116. s to the resulting illegal position which was played over the board 6 Release the Edit button to exit edit mode 7 Make sure the right player is on turn by clicking on the checker image for the player on roll under the game board 8 Continue to enter the rest of the game 8 3 Analyzing matches GNU Backgammon can analyze your matches for skill and luck If you have an open match as a result of playing loading or importing the analysis is started by choosing Analyze Analyze match You should now see a progress bar at the bottom right corner of the main interface window while the computer is busy analyzing During this time you won t be able to interact with the program other than to quit the analysis The analysis is complete when the progress bar disappears and you hear a small sound Now you would probably like to view the result of the analysis This can be done in terms of overall statistics by choosing Analyze Match statistics or in detail by browsing through the match More on these subjects in the upcoming sections You can also analyze just the current game by choosing Analyze Analyze game If you re only interested in the analysis of the current move you can select Analyze Analyze move 8 3 1 Analysis settings You can configure how GNU Backgammon analysis the match or game for you This can be configured in the dialog box that appears when choose Settings Analysis GNU Backgammon Manual V0 16 35
117. stribution of 0 100 100 0 0 0 gives a NEMG of 3 whereas the corresponding money equity is only 2 This is because the gammon price is high for that particular score When both players are far from winning the match e g 0 0 to 17 or 1 0 to 17 NEMG is very close to the usual money equity NEMG can be calculated from both cubeless and cubeful MWCs A word of caution A cubeless NEMG calculated from a cubeless MWC could be named cubeless equity but in most backgam mon literature this term seems to be reserved for the cubeless money equity 11 5 5 Cubeful equities This chapter is a brief description of how GNU Backgammon calculates cubeful equities The formula build directly on the work by Rick Janowski Take Points in Money Games from 1993 11 5 5 1 Basic formula for cubeful equities The basic formula for cubeful equities as derived by Janowski is E cubeful E dead 1 x E live x where E dead is the dead cube equity cubeless equity calculated from the standard formula E live is the cubeful equity assuming a fully live cube We ll return to that in the next section x is the cube efficiency x 0 gives E cubeful E dead as one extreme and x 1 gives E cubeful E live as the other extreme In reality x is somewhere in between which typical values around 0 6 0 8 Janowski s article doesn t mention cubeful equities so we use the straightforward generalization GNU Backgammon Manual V0 16 61 82 MWC cubeful
118. t between a raw board encoding the number of checkers on each point and these keys IDs is available licensed under GPL 3 Thanks to Tom Keith and David desJardins for their suggestions on simplifying the encoding without increasing the worst case length 11 7 A technical description of the Match ID This section describes how the match ID is calculated The match ID can be used for easy exchange of positions for gnubg users in conjunction with the position ID The match key is a 9 byte representation of the match score match length value of cube GNU Backgammon Manual V0 16 67 82 owner of cube Crawford game flag player on roll player to make a decision doubled flag resigned flag and the dice rolled The match ID is the 12 character Base64 encoding of the match key Match key The match key is a bit string of length 66 GNU Backgammon Manual V0 16 68 82 1 4 5 6 7 8 9 11 12 13 14 15 Cube CubeOwner DiceOwner Crawford GameState TurnOwner Double Resign 1 Bit 1 4 contains the 2 logarithm of the cube value For example a 8 cube is encoded as 0011 binary or 3 since 2 to the power of 3 is 8 The maximum value of the cube in with this encoding is 2 to the power of 15 i e a 32768 cube 2 Bit 5 6 contains the cube owner 00 if player 0 owns the cube 01 if player 1 owns the cube or 11 for a centered cube 3 Bit 7 is the player on roll or the player who did roll 0 and 1 for play
119. t least World Class here My experience on a 700MHz PC is that a 7 point match takes about 15 to 20 minutes to analyze on the Supremo settings But the results tend to be very accurate 10 1 7 Rollouts Settings Rollouts General Settings tick the boxes for Cube decisions use same settings same as checker play and Use same settings for both players Settings Rollouts First Play Both select Expert here this is my opinion When doing rollouts most of the time Expert play will be more than strong enough if you do say 1296 trials with no truncation The rollout function has an enormous number of options most of which are only useful when trying to investigate special positions The simple expert setting for both players 1s probably more accurate than any of the Analysis functions The downside is that rolling out 1296 trials of an early move in a game can take a couple of hours On World Class or Supremo rollout settings it can take more than 24 hours of computing time 10 1 8 Changing evaluation settings A typical evaluation settings dialog is shown in this figure GNU Backgammon Manual V0 16 45 82 SS GNU Backgammon Evaluation settings Chequer play Cube decisions Predefined settings Predefined settings Select a predefined setting Select a predefined setting user defined wel user defined lal User defined settings User defined settings Lookahead Lookahead Plies lo Plies 0 Reduce
120. terface 3 3 Mac OSX Once you have installed both an X11R6 server and GNU Backgammon for MacOS X you can run GNU Backgammon for MacOS X by 1 Start your X11R6 server 2 Once your X11R6 server is running in one of its Terminal windows by default Apple s X11 opens one such window at start up and XDarwin opens three do the following a If you have installed GNU Backgammon in your private Applications folder type cd Applications gnubg to get into GNU Backgammon for MacOS X s folder and then type gnubg to run it b If you have installed GNU Backgammon in the global top level Applications folder type cd Applications gnubg to get into GNU Backgammon for MacOS X s folder and type gnubg to run it 3 4 Command line options The following options control the startup of GNU Backgammon Most options are available in all versions of GNU Backgammon but notably the w and t options don t work under MS windows where separate command line and GUI applications exist instead GNU Backgammon Manual V0 16 18 82 Example 3 1 GNU Backgammon startup options Usage gnubg OPTION file sgf Help Options Rh aes Show help options help all Show all help options RELE HEI Show GTK Options GTK Options class CLASS Program class as used by the window manager name NAME Program name as used by the window manager SC BSSENSZO CREEN MES reel CO VSE sync ake X calls synchronous
121. th the s option It s recommended to set the cache size to the maximum amount of memory available although there is no need to set it beyond the size of the bearoff database to be generated Other options for makebearoff are available see makebearoff help for the complete set The accompanying program makehyper is used to generate databases for Hypergammon For example to generate the 3 checker database issue the command makehyper c 3 f hyper3 bd Since the generation is very time consuming makehyper will generate a checkpoint file in the example above hyperl bd tmp that can be used to restart the calculation if needed by using the r option You can also change the default convergence threshold of 0 00001 if you re happy with less accurate equities To generate the 3 checker database you need approximately 400 MB of free memory On a 2 4 GHz box with 512 MB of RAM the calculation ran for 58 iterations of 3000 seconds each i e a total of 48 hours See makehyper help for the complete set of available options GNU Backgammon Manual V0 16 55 82 11 1 2 Download You may download the two sided database with 6 checkers on 6 points from ftp alpha gnu org gnu gnubg gnubg_tsO bd gz and the one sided database with 15 checkers 6 points from ftp alpha gnu org gnu gnubg gnubg_os0 bd gz Later other databases may be available for download or it may be possible to purchase these on CDROM or DVD for a nominal fee 11 1 3 Ve
122. that the bearoff trays change side when the board is displayed with clockwise movement 7 4 Quick edit The default method of editing a position is called Quick edit It s based on clicking on the point where you want to place checkers The number of checkers placed on the point is depending on where you click for example if you want to place 3 checkers on a point clicking on the location where the third checker would go places 3 checkers This method should be familiar to Snowie users Clicking with the left button places checkers for player1 clicking with the right button places checkers for player2 If you want to place more than 5 checkers click multiple times on the tip of the point To clear a point click on the border of the board below or above the point depending on if the point is in the lower or top half of the board The bar works just like normal points the more you click to the middle of the bar the more checkers will be placed there 7 5 Editing by drag and drop There is also a different way of editing the checker positions You can drag and drop checkers around the board while you re holding down the Ctrl key on your keyboard Press the Ctrl key and hold it down Then left click the checker you want to drag to another point and drag it with the mouse while holding down the Ctrl key and the left mouse button to the destination point You can drag checkers to open points or to points where you have checkers of the same co
123. the procedure described above with the following improvements 1 Truncation instead of rolling out all the way to the end of the game it can stop and pretend its evaluation after a few plies is perfect This may obviously introduce some amount of systematic error but in practice this may not matter because 2 it makes rollouts much faster which means you can do more of them and thus trade sampling error for systematic error 3 different positions will be reached in different trials so the correlation between errors in each trial weakens and the errors cancel out to some extent 4 if you are rolling out the positions after making different plays then any remaining systematic error between the two rollouts is likely to be somewhat correlated and so the error in the comparison between the plays is hopefully small This implies that truncated rollouts are better for estimating relative equity which is the better move here 13 10 9 or 13 10 6 5 than absolute equity at this match score I need 29 wins to accept a dead cube can I take in this position 5 Race database truncation when the game enters its 2 sided bearoff database GNU Backgammon can estimate the proba bility of winning from that position with no error at all it can play and evaluate endgame positions perfectly which saves time and avoids introducing the errors that can result from large equity variances at the end of the game 6 Variance reduction when using look
124. this example White and Black are playing a 5 point match After three games White has 4 points which is just one point short of what he needs That triggers the Crawford rule which says there can be no doubling in next game Game 4 There is no bonus for winning more than the required number of points in match play The sole goal is to win the match and the size of the victory doesn t matter Automatic doubles beavers and the Jacoby rule are not used in match play 3 Starting GNU Backgammon 3 1 Linux and Unix If GNU Backgammon is properly installed on your system you can start it by simply typing gnubg at the command prompt If you want to start the GNU Backgammon command line interface you can type gnubg tty or gnubg t With this option GNU Backgammon starts without the graphic user interface There is also other options which can be added at the start up 3 2 Microsoft Windows The builds of GNU Backgammon which may be downloaded from the main GNU Backgammon page comes with an installation system The installation system will create a launch menu item in your start menu Usually the menu item can be found by choosing Start Programs GNU Backgammon GNU Backgammon for Windows GNU Backgammon also has a command line interface This is supplied as a separate executable file on Microsoft Windows You can start this version of GNU Backgammon by choosing Start Programs GNU Backgammon GNU Backgammon Command Line In
125. tion Entitled XYZ according to this definition The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document These Warranty Disclaimers are considered to be included by reference in this License but only as regards disclaiming warranties any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License D VERBATIM COPYING You may copy and distribute the Document in any medium either commercially or noncommercially provided that this License the copyright notices and the license notice saying this License applies to the Document are reproduced in all copies and that you add no other conditions whatsoever to those of this License You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute However you may accept compensation in exchange for copies If you distribute a large enough number of copies you must also follow the conditions in section3 You may also lend copies under the same conditions stated above and you may publicly display copies E COPYING IN QUANTITY If you publish printed copies or copies in media that commonly have printed covers of the Document numbering more than 100 and the Document s license notice requires Cover Texts you must enclose the copies in covers that carry clearly and legibly all these Cover Texts Front Cover Texts on th
126. tween the games and moves lt a c gt Y CN e Game 1 gnubg 0 use d gnubg user D Z bo Sys 972 BRT 24135 3 26 23 21 13 7 45 15 11 13 8 4 32 2461 75 Si 13 7 5 52 21 14 11 bar 24 6 503 amp 61 14 8 6 5 25 13 67 7 Double to 2 Take 8 53 21 13 36 24 15 9 51 13 7 13 15 11 10 23 7 4 3 1 66 13 7 2 11 5 6 2 11 54 13 9 13 8 24 3 6 8 4 12 23 5 6 35 di FEF 13 36 13 7 8 5 34 204709 14 46 9 378 62 7 5 ESO 15 65 bof Soff 26 bof Zor 16 22 oM Bd Bolt dor 17 22 boff 6 4 26 Goff 5 3 19 41 dior L o 15 Sfoff 2 2 19 46 Eso gio dd 62 41021 dor 20 11 5 4 3 folF den 5o Bor 21 46 Soff do 221 o 2 fort 22 13 3 2 3folF Redouble ta 4 23 Take 66 2 off 1 off 2 U Figure 18 The Game record pane The figure shows a typical game record list The moves are shown in two columns The left column shows the moves for player 0 the to player and the right column shows the moves of player 1 the bottom player You can navigate through the game with the arrow buttons at the top of the game record The red buttons with the double arrows take you to the previous game or the next match Arrow pointing to the left takes you to the previous game and the red arrow pointing to the right takes you to the next game The green buttons take you one move ahead in the game or one move back The green arrow button pointing to the right take you to the previous move The green arrow button pointing to the right take you to the next move or to
127. ual V0 16 11 3 2 Match description gnubg match returns a dictionary containing the following items match info General match info games A sequence one element per game stats optional Match statistics 11 3 3 Match info A dictionary containing the following items match length variation One of Standard Nackgammon Hypergammon Hypergammon2 or Hypergammon3 rules optional Additional rules used A subset of NoCube Crawford and Jacoby X O Per player information Each a dictionary containing rating and name annotator optional round optional place optional date optional Sequence of Day Month Year event optional default eval context Default evaluation context A dictionary in the same format as returned by evalcontext default rollout context Default rollout context Example gt m match info 58 82 match length 25 rules Crawford default eval context plies 2 deterministic 1 reduced 0 noise 0 0 cubeful 1 annotator GNU 0 14 O rating 0 Exp 0 name Moshe Tissona round Final place Monte Carlo variation Standard default rollout context n truncation 11 initial position O trials O stop on std 0 variance reduction 1 late eval 0 truncated rollouts 0 truncate bearoff2
128. ver you can export a position to EPS and include this EPS file in your LaTeX document 8 2 Entering live tournament matches It s possible to enter match transcriptions into GNU Backgammon It s not very difficult Presuming you re using the GUI do this 1 Start a match of any length pressing the New button and select Human Human and manual dice 2 To select the opening roll click on the right dice pair in the dice selection window that appears The left die in the dice pair is the die that s rolled by player 0 or the player at the top The right die is the die that will be rolled by player 1 or the bottom player So if you select for example the 53 dice combination it means that player O rolls a 5 and player 1 rolls a 3 and player 0 is therefore beginning this game However if you select the 35 dice combination it means that player 0 rolls a 3 and player 1 rolls a 5 Player 1 will therefore begin when you select 53 instead of 35 3 To change the names use the Edit button at the top If you want to enter information such as the name of the Annotator date locale etc go to the Game menu and choose Match Information 4 To enter written comments you first have to play the move and then go back to the move in the move list to be able to use the Commentary pane feel free to close the Messages pane from the Windows menu Don t forget to save the match every once in a while 5 One comment when entering the Cube commentary
129. w is the error rate determined aD 12 6 7 What does Pips mean 2 e R R R E RRR RRR RRR RRR RRR RRR 76 12 6 8 What does epemean so SC Re ee eG Re ee 76 12 7 Databases o ooe 0554 bw e ka a e RRR eR a eA Ak ee ee ae a ee vi 12 7 1 What is the Database menu for 2 2 ee a US Abbreviations xc ys Sek Wk BEES Re we a TE BAe a ad Oe eA ole Byes Oe oe ede Se 77 128 1 GWC 2355 4 4 G05 ake pO RE Boe ea eR Ee ee ee ee eee Lee a 77 1282 MWC rd es be Be a ee ee ee ee ee ee ee ee Boe eS OF FS 1283 DP 2 A Pee ER eee E E Pe T TR A Dee e TI 12 84 CP a e ra A AAA e oe A eae As Se TI 1285 T e peints eaka kah eae eee dw eee eee a e eee Pee A ew REA ye 8 ea 77 IESO L ood eek eee ke E ee E ee Se ee a Oo 78 A GNU Free Documentation License 78 B PREAMBLE 78 C APPLICABILITY AND DEFINITIONS 78 GNU Backgammon Manual V0 16 D VERBATIM COPYING COPYING IN QUANTITY MODIFICATIONS G COMBINING DOCUMENTS H COLLECTIONS OF DOCUMENTS AGGREGATION WITH INDEPENDENT WORKS TRANSLATION K TERMINATION FUTURE REVISIONS OF THIS LICENSE M ADDENDUM How to use this License for your documents 9 82 79 79 80 81 81 81 81 82 82 82 GNU Backgammon Manual V0 16 List of Figures VD 0 QQ Un A UU Ne WO Ww Ww N N N N N N NY N N NO eRe a o om oo ked N O Oo WON Dn FF WN KF O O ONOGA A WYN KF O 10 82 A board with the checkers in their initial position ee 13 Direction of movement of White s che
130. wins gammons backgammons losses gammon losses backgammon losses Rank the moves based on this evaluation For one ply after doing the above step GNU Backgammon chooses the best n moves where n is set by the move filters For each one it takes the resulting position for that move and goes through all 21 possible dice rolls for the opponent From these results it works out the average expectation for the initial move and ranks them This is the same as Snowie 2 ply You can think of it as asking what s my best move if I also consider every possible dice roll and move my opponent might make For 2 ply Snowie 3 ply a similar process is done but this time not only are the opponents possible moves considered but for each of these the player on roll s next move will be considered as well For a single move on average there are about 20 legal moves to consider When doing a one ply analysis evaluation for the top n moves from the move filter GNU Backgammon needs to consider 21 rolls by the opponent 20 and possible legal moves per roll 420 positions to evaluate Every additional ply will multiply the previous number of evaluations by about 400 odd which explains the huge difference in playing speed analysis speed between 0 ply and 2 ply settings I don t think many people would enjoy playing against GNU Backgammon at 3 ply settings where moves could take minutes to be selected It s also not clear that using much deeper lookahead a
131. witch the players sides Go to the menu Game and click on Swap players 12 6 5 What do and mean After analyzing a game or a match GNU Backgammon is able to do some comments on checker play or cube decisions Open the menu Window Game record and you will see a list of the moves If the actual move or cube decision differs from the best GNU Backgammon will put a comment on it The default settings are 0 040 doubtful 2 0 080 bad 0 160 very bad 22 You may change these comment in the menu Window Annotation choosing another comment for moves and or double Note Why a move should be deemed worse than a move that s one of life s little mysteries 12 6 6 How is the error rate determined GNU Backgammon determines a player s strength according to it s average error per move Average Error Skill Level 0 000 0 005 Extra terrestrial GNU Backgammon Manual V0 16 76 82 0 005 0 010 World class 0 010 0 015 Expert 0 015 0 020 Advanced 0 020 0 025 Intermediate 0 025 0 030 Beginner 0 030 Novice After analyzing a game match or session you can see the summary in the menu Analyze statistics Note that you can t change the ranges of these values 12 6 7 What does Pips mean The pip count is a measurement showing the total number of pips required for a player to bear off al
132. y equity This is the value of the position in money game e g if your equity is 0 4 an you are playing money game with a 1 stake you will win 0 40 on average The money equity can be calculated with or without taking the effect of the double cube into consideration or cubeful or cubeless The cubeless equity can be calculated from the basic formula 2 p w 1 2 p wg p g 3 p wbg p lbg Evaluating the cubeful equity is much more difficult it can either be estimated from the cubeless equity by using transformations as outlined by Rick Janowski or by constructing a neural net that directly outputs cubeful equities GNU Backgammon uses the former approach Section 11 5 5 11 5 3 Match Winning Chance In match play we re generally not particular interested in the outcome of the individual games as much as the outcome of the entire match so the interesting quantity for match play is match winning chance MWC As for the money equity the MWC can be calculated with and without the effect of the double cube The MWCs are generally calculated with the use of a match equity table which contains the chance of winning the match before a game starts e g 1f the score is 0 0 in a 1pt match each player has 50 chance of winning the match before the game starts assuming they re of equal skill GNU Backgammon Manual V0 16 60 82 The cubeless MWC is calculated as MWC cubeless p w MWC w pU MWC 1 p wg MWC wg p lg MWC lg p w
133. y the number of close or actual cube decisions Note that is different from Snowie 4 that defines the error rate per cube decision as the total error rate divided by the total number of moves for both players In general your error rate per cube decision will be lower in Snowie than in GNU Backgammon Note that the reported number is multiplied by 1000 in the default settings Cube decision rating GNU Backgammon will assign a rating for your cube decisions ranging from Awful to Supernatural See the description for the overall rating below 8 4 3 4 Overall rating The last section is the overall summary 1 2 Error rate total The accumulated checker play and cube decision errors reported by normalized and unnormalized Error rate per decision The error rate per decision is the total error rate divided by the number of non trivial decisions i e the sum of unforced moves and close or actual cube decisions Again please note that is different from Snowie 4 that defines the error rate per decision as the total error rate divided by the total number of moves for both players In general your error rate per move will be lower in Snowie than in GNU Backgammon An investigation of approximately 300 matches showed the on average the GNU Backgammon error rate with be 1 4 times higher than your Snowie 4 error rate Equivalent Snowie error rate For easy comparison GNU Backgammon will also print the total error rate calculated by the

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