1
@author Achim Mueller <ace@gnubg.org>
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@chapter Frequently Asked Questions
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@cindex frequently asked questions
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This chapter documents the most frequently asked questions. Sources include
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the newsgroup @uref{news:rec.games.backgammon,, rec.games.backgammon}, the
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@uref{mailto:bug-gnubg@@gnu.org,, @gnubg{}-mailinglist} and the
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@uref{http://www.gammonline.com,, discussion board of @emph{GammOnLine}}.
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* Installation questions::
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* Gnubg startup questions::
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* Backgammon playing questions::
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* Settings questions::
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* Analysis questions::
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* Database questions::
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* Some Backgammon and technical terms::
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@node General questions
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@section General questions
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* What is GNU Backgammon?::
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* Which operating systems are supported?::
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* Where can I download it?::
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* Do I have to pay for GNU Backgammon?::
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* This GNU stuff sounds interesting::
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* Learn more about backgammon::
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* What is Hypergammon?::
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* What is Nackgammon?::
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* Where do I get more documentation about GNU Backgammon?::
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* I have read all the documentation but I still have questions::
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* I probably found a bug. What shall I do now?::
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* I have some suggestions and new ideas for improvements::
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* This F.A.Q. is full of typos and in bad English.::
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@node What is GNU Backgammon?
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@subsection What is GNU Backgammon?
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GNU Backgammon (@gnubg{}) is software for playing and analysing backgammon
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positions, games and matches. It's based on a neural network. Although it
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already plays at a very high level, it's still work in progress. You may
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play GNU Backgammon using the command line or a graphical interface
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@node Which operating systems are supported?
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@subsection Which operating systems are supported?
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Currently GNU Backgammon is specifically designed for @emph{GNU/Linux}. It
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also compiles and (hopefully) runs under @emph{*BSD, IRIX, Solaris} and
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@emph{True64 Unix}. Last but not least there are downloads available for
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@emph{MS Windows}, @emph{MS DOS} and @emph{MacOSX}. If you successfully port
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GNU Backgammon to another operating system please let us know, contact
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@uref{bug-gnubg@@gnu.org}.
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@node Where can I download it?
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@subsection Where can I download it?
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The official website is
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@uref{http://www.gnubg.org/}. You can get daily snapshots at
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@uref{ftp://alpha.gnu.org/gnu/gnubg/snapshots/}. @emph{MS
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Windows} binaries are available at @uref{http://home.online.no/%7Eoeysteij/}.
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Daily @emph{MS Windows} builds are downloadable from Nardy's homepage at
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@uref{http://users.skynet.be/bk228456/GNUBgW.htm}
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@emph{GNU/Linux}-Rpm's are available at
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@uref{http://www,acepoint.de/}. And a download for @emph{MacOSX}
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can be found at @uref{http://mapage.noos.fr/gnubgosx/}.
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@node Do I have to pay for GNU Backgammon?
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@subsection Do I have to pay for GNU Backgammon?
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GNU Backgammon is free software and belongs to the @emph{GNU Project}. For
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more information see the @uref{http://www.gnu.org/licenses/gpl.html,, GNU
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General Public License}. But be aware that GNU Backgammon is not
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@emph{public domain software} or @emph{shareware} as used in
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@node This GNU stuff sounds interesting
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@subsection This GNU stuff sounds interesting
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The best starting point is @uref{http://www.gnu.org,, GNU's homepage}.
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@node Learn more about backgammon
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@subsection Learn more about backgammon
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@uref{http://www.bkgm.com,, Backgammon Galore} is a site that lives up
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to its name. And an extensive collection of links is maintained at
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@uref{http://www.chicagopoint.com/links.html,, Chicago Point links}.
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@node What is Hypergammon?
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@subsection What is Hypergammon?
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Hypergammon is a variety of backgammon with only three checkers for
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each player. Both players start with their checkers on the 22-/23- and 24-point.
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Rules a like the original backgammon rules. Winning/Loosing a gammon or
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backgammon is also possible.
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@node What is Nackgammon?
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@subsection What is Nackgammon?
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Nackgammon is a variety of backgammon with exactly the same rules. The
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only difference is the starting position. Both players take a checker
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from their 6- and 13-point and put them back on the 23-point.
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@node Where do I get more documentation about GNU Backgammon?
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@subsection Where do I get more documentation about GNU Backgammon?
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Albert Silver has written a wonderful tutorial for playing GNU Backgammon
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on @emph{MS Windows}. See @uref{http://www.bkgm.com/gnu/AllAboutGNU-1.0/AllAboutGNU.html}
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@node I have read all the documentation but I still have questions
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@subsection I have read all the documentation but I still have questions
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Send emails to the @uref{mailto:bug-gnubg@@gnu.org,,
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@gnubg{}-mailinglist}. If you've found a bug, please be sure to include
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details of your operating system, the version of @gnubg{} you're using and
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any error messages. Try to describe exactly what is happening before the
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@node I probably found a bug. What shall I do now?
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@subsection I probably found a bug. What shall I do now?
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Either send an e-mail to the @uref{mailto:bug-gnubg@@gnu.org,, @gnubg{}-mailinglist},
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or use the menu @option{Help/Report bug} to fill out an online bug report. Please make
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sure that the bug you found was not reported and/or fixed before.
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@node I have some suggestions and new ideas for improvements
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@subsection I have some suggestions and new ideas for improvements
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Wonderful! Send e-mails to the
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@uref{mailto:bug-gnubg@@gnu.org,, @gnubg{}-mailinglist}.
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@node This F.A.Q. is full of typos and in bad English.
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@subsection This F.A.Q. is full of typos and in bad English.
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Probably you are right. But you are cordially invited to send
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corrections to @email{info@@gnubg.org}. And keep the following
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@cite{Documentation is like sex: when it is good, it is very, very good,
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and when it is bad, it is better than nothing.}
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@node Installation questions
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@section Installation questions
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* Where do I find a version for my operating system?::
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* Do I need additional software to run GNU Backgammon?::
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* Installing newer versions::
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* Compiling it from the source code::
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* What software do I need for compiling under @emph{GNU/Linux}?::
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* What software do I need for compiling under @emph{MS Windows}?::
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* It does not compile::
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@node Where do I find a version for my operating system?
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@subsection Where do I find a version for my operating system?
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@emph{MS Windows} binaries are available at
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@uref{http://home.online.no/%7Eoeysteij/}. Nardy Pillard has published
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an excellent page at @uref{http://users.skynet.be/bk228456/GNUBgW.htm,, Windows build}.
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@emph{GNU/Linux}-Rpm's are available at
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@uref{http://mole.dnsalias.org/~acepoint/} or @uref{http://www.acepoint.de}.
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And a download for @emph{MacOSX} can be found at @uref{http://mapage.noos.fr/gnubgosx/}.
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@node Do I need additional software to run GNU Backgammon?
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@subsection Do I need additional software to run GNU Backgammon?
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No, everything is included in the binaries.
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@node Installing newer versions
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@subsection Installing newer versions
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If you are using a @emph{MS Windows} operating system make a copy of
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either @file{.gnubgrc} or @file{.gnubgautorc} and
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@file{.gnubgmenurc}. You will find them in either @file{c:} or the home
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directory of your GNU Backgammon (for instance: @file{c:\program
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files\gnubg\}). After you have installed the new version, copy them
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If you are working with @emph{GNU/Linux} these files are
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probably in your home directory (@file{~/}). They won't be overwritten
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by installing a new version of GNU Backgammon, but it's always a good
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idea to keep backup files.
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@node Compiling it from the source code
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@subsection Compiling it from the source code
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Good luck to you! Download the source code and read either: @ref{What
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software do I need for compiling under @emph{GNU/Linux}?}, @ref{What
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software do I need for compiling under @emph{MS Windows}?}.
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Good luck to you! Download the source code and read either: What software
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do I need for compiling under @emph{GNU/Linux}, What software do I need for
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compiling under @emph{MS Windows}.
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@node What software do I need for compiling under @emph{GNU/Linux}?
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@subsection What software do I need for compiling under @emph{GNU/Linux}?
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Depending on the distribution you are working with:
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@item @uref{ftp://alpha.gnu.org/gnu/gnubg/snapshots/,, GNU Backgammon
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@item a @emph{"C-"}compiler
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@item autoconf and automake
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@item xdevel (for the graphical interface)
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@item gtk+ >= 1.2 (for the graphical interface)
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@item gtkglarea (optional for the 3d-board)
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@item gtkglext (optional for the 3d-board)
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@item python (optional for the python shell)
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@item guile (optional, for invoking your own macros)
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@item gdbm (optional, for using your own databases)
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Unpack the GNU Backgammon snapshots and follow the instructions given in
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the @file{INSTALL} file.
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@node What software do I need for compiling under @emph{MS Windows}?
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@subsection What software do I need for compiling under @emph{MS Windows}?
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Nardy Pillards has published an excellent instruction guide for making a
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@uref{http://users.skynet.be/bk228456/GNUBgW.htm,, Windows build}.
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@node It does not compile
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@subsection It does not compile
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Check that you've installed all necessary development packages. All you
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need should be listed in either
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@emph{GNU/Linux}:@ref{What software do I need for compiling under
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@emph{MS Windows}:@ref{What software do I need for compiling under
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Check that you have installed all necessary development packages. All you
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need should be listed in either
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@emph{GNU/Linux}: What software do I need for compiling under
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@emph{MS Windows}: What software do I need for compiling under
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Look for warnings or errors during compiling. If you still don't have a
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clue, contact the @uref{mailto:bug-gnubg@@gnu.org,,
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@gnubg{}-mailinglist}.
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@node Gnubg startup questions
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@section Gnubg startup questions
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* I get an error message at the start::
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* GNU Backgammon complains about missing files::
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* Starting from the @emph{WinXP} menu it plays like a beginner::
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* My screen mixes up while starting GNU Backgammon::
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* How do I make GNU Backgammon remember the size and place of the windows?::
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* I only get a command-line interface -- where is the nice board?::
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* When I restart GNU Backgammon all my settings are lost::
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* I do not need all the graphics -- where is the command terminal?::
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@node I get an error message at the start
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@subsection I get an error message at the start
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Your computer is trying to tell you something, give it a chance and read the
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messages. Then read the next items carefully @enddots{}
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@node GNU Backgammon complains about missing files
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@subsection GNU Backgammon complains about missing files
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GNU Backgammon is probably missing either the file @file{gnubg.weights}
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or @file{gnubg.bd}. @file{Gnubg.bd} is the bearoff database used to
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evaluate endgame positions.
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The file @file{gnubg.weights} contains the trained neural net weights
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for most of @gnubg{}'s position evaluators. Like @file{gnubg.bd}, it should
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be kept in either the current directory or the installed directory.
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@node Starting from the @emph{WinXP} menu it plays like a beginner
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@subsection Starting from the @emph{WinXP} menu it plays like a beginner
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Open the @emph{MS Windows} menu and go to the entry of
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@gnubg{}, then right-click with the mouse and choose
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@option{properties}. Check if the @option{working path} is the same
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directory as the @file{*.exe}-file one line above. If not, adjust the
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@node My screen mixes up while starting GNU Backgammon
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@subsection My screen mixes up while starting GNU Backgammon
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Install the newest driver for your graphic card. Be sure that you have
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chosen a desktop resolution of at least 65535 (16 bit colour depth). If
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your card is an @emph{ATI Rage "something"} there might be some problems
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with the graphical interface (GTK+) and @emph{MS Windows}.
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@node How do I make GNU Backgammon remember the size and place of the windows?
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@subsection How do I make GNU Backgammon remember the size and place of the windows?
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@node I only get a command-line interface -- where is the nice board?
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@subsection I only get a command-line interface -- where is the nice board?
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@emph{MS Windows} users should click on the correct menu entry (@option{GNU
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Backgammon for windows}). If this doesn't work, check whether you have the
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file @file{c:\[path-to-your-gnubg]\gnubg.exe}.
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@emph{GNU/Linux} users should check if @uref{http://www.gtk.org/,, GTK+} is
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@node When I restart GNU Backgammon all my settings are lost
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@subsection When I restart GNU Backgammon all my settings are lost
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Did you previously save your settings (menu @option{Settings, Save settings})?
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If you have just installed a newer version of GNU Backgammon go to @ref{Installing
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@node I do not need all the graphics -- where is the command terminal?
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@subsection I do not need all the graphics -- where is the command terminal?
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For @emph{GNU/Linux} users: open a terminal and start @gnubg{} with the
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@emph{MS Windows} users: Look for @file{gnubg-no-gui.exe}
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in @gnubg{}'s directory or open the @emph{MS Windows} menu
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@option{execute} and type @file{c:\[path-to-your-gnubg]\gnubg-no-gui.exe}.
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There is also the menu entry @option{GNU Backgammon Command Line Interface}.
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@node Backgammon playing questions
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@section Backgammon playing questions
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* What is the difference between starting a new game or match or session?::
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* How do I move the checkers?::
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* Can I place more than 5 checkers on a point?::
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* GNU Backgammon is a poor player::
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* GNU Backgammon plays too strong for me::
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* I think this bot is cheating by rolling better dice::
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@node What is the difference between starting a new game or match or session?
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@subsection What is the difference between starting a new game or match or session?
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When you start a new match you will be asked to play to a certain
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match length (for example, 7 points). The player who first reaches
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this score wins the match. The default for match play has the Crawford
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Rule (see @uref{http://www.bkgm.com/glossary.html#crawford_rule,,
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Backgammon Galore: Crawford rule}).
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Starting a new session means playing an unlimited number of games. You may
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stop the session at any time and save it. The default for sessions has
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@uref{http://www.bkgm.com/glossary.html#jacoby_rule,, Backgammon Galore:
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If you choose to play a new game, GNU Backgammon will open the last
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saved match or session you were previously playing. When there isn't a saved
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match or session it will start a new unlimited session.
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@node How do I move the checkers?
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@subsection How do I move the checkers?
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The easiest way to move checkers is to @emph{"drag and drop"}. Put your
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mouse over the checker you wish to move, press and hold the left mouse button
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and drag the checker to the desired point.
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If you simply click then the left mouse button moves a checker the amount
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shown on the left die, and the right mouse button moves a checker the amount
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shown on the right die.
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To always display the higher number on the left go to the menu
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@option{Settings, Appearance, General} and activate @option{Show higher
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@node Can I place more than 5 checkers on a point?
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@subsection Can I place more than 5 checkers on a point?
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Standard international backgammon tournament rules allow up to all 15 checkers
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on a single point. If you wish to play with a maximum of 5 checkers, go to
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the menu @option{Settings} and activate the @option{Egyptian Rule}.
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@node GNU Backgammon is a poor player
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@subsection GNU Backgammon is a poor player
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Are you sure? If you are then you should @emph{definitely} enter the
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@uref{http://www.backgammon-tournaments.com/,, Backgammon World Championship}
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Otherwise check whether the file @file{gnubg.weights} is correctly
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installed, also see @ref{GNU Backgammon complains about missing files}.
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@node GNU Backgammon plays too strong for me
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@subsection GNU Backgammon plays too strong for me
426
Go to the menu @option{Settings, Players} and change the values of
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@option{Player 0}. There are also some predefined settings you may
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@node I think this bot is cheating by rolling better dice
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@subsection I think this bot is cheating by rolling better dice
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In the menu @option{Settings} you may choose between different random dice
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generators. If you still think GNU Backgammon is cheating, program your
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own dice generator or roll manually.
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@node Settings questions
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@section Settings questions
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* Where can I change the name of the human player?::
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* Where are the player records saved?::
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* Where are all the settings stored?::
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* How do I change the colours?::
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* How do I stop the annoying beeps?::
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* What are "plies"?::
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* What is "reduced evaluation"?::
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* Where do I get the images for exporting positons and matches?::
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@node Where can I change the name of the human player?
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@subsection Where can I change the name of the human player?
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Go to the menu @option{Settings, Players ...} and click on @option{Player
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1}. At the top there is a field where you can change the human player's name.
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@node Where are the player records saved?
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@subsection Where are the player records saved?
460
The player records are stored in a file called @file{gnubgpr}. On @emph{linux systems}
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this file will be saved in ~/.gnubg/. On @emph{MS Windows} you can find this file in
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the directory of gnubg, i.e. C:\Program Files\Gnubg\. It's alway a good idea to make
463
a periodically backup of this file and of @file{.gnubgautorc}.
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@node Where are all the settings stored?
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@subsection Where are all the settings stored?
467
The settings are stored in a file called @file{.gnubgautorc}. On linux this file is
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in your home directory, on @emph{MS Windows} in the same directory as the program
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@node How do I change the colours?
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@subsection How do I change the colours?
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Go to the menu @option{Settings, Appearance}. Here you may change the colours
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of checkers, points and the board itself.
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@node How do I stop the annoying beeps?
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@subsection How do I stop the annoying beeps?
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Go to the menu @option{Settings, Appearance} and click on the card
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@option{General} at the right. Disable the option @option{Beep on illegal input}.
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@node What are "plies"?
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@subsection What are "plies"?
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A @emph{ply} describes how far GNU Backgammon evaluates the position.
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@emph{"0-ply"} means GNU Backgammon estimates the worth of the
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position as it is. A @emph{"1-ply"} evaluation looks one step deeper.
488
GNU Backgammon also evaluates positions that may occur one roll
489
further. @emph{"2-ply"} is another roll further and so on.
491
The more plies you choose the stronger GNU Backgammon becomes. But
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keep in mind that it will also decrease its playing speed.
494
Note that @emph{"0-ply"} in GNU Backgammon is equivalent to the
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@emph{"1-ply"} evaluation of Snowie.
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@node What is "noise?"
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@subsection What is "noise?"
500
Noise is a way of reducing GNU Backgammon's @ref{What are
501
"plies"?,, 0-ply} evaluation. Increasing the noise decreases its playing
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@node What is "reduced evaluation"?
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@subsection What is "reduced evaluation"?
507
It's a method for cutting down the searching for candidate moves to increase
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speed. Reduced evaluations only work with 2-ply and deeper.
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@node Where do I get the images for exporting positons and matches?
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@subsection Where do I get the images for exporting positions and matches?
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You may use different images to export positions, sessions or matches into html.
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@emph{GNU Backgammon} creates its own set of images when you go to the menue
515
@option{file/export/HTML images ...} and select a path. If you want to use BBS- or
516
fibs2html-images, download them from Nardy's page at
517
@uref{http://users.skynet.be/bk228456/GNUBgW.htm}.
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If you want to export @uref{http://www.gammonline.com,, GammOnline} positions you
520
can do this by using @option{Edit/Copy as/GammOnline (HTML)}. Note that you have to
521
download the images from @uref{http://www.gammonline.com/members/imgcopy.htm}. You have
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to be a member for accessing these images.
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@node Analysis questions
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@section Analysis questions
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* What is a position ID and match ID?::
530
* How do I manually create a position?::
531
* How can I remove checkers from the bar?::
532
* Which formats can I use to import positions?::
533
* Which formats can I use to import matches?::
534
* How can I switch the players sides?::
535
* What do "!" and "?" mean?::
536
* How is the error rate determined?::
539
@node What is a position ID and match ID?
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@subsection What is a position ID and match ID?
542
You will find two small fields titled @option{Position} and @option{Match
543
ID} at the top left of the GNU Backgammon window. Here you may use the
544
@option{position_id}- or @option{match_id}-format for setting up or
547
An explanation of both formats will (hopefully soon) follow in GNU
548
Backgammon's documentation.
550
@node How do I manually create a position?
551
@subsection How do I manually create a position?
553
Open a new game, match or session. If @gnubg{} has already rolled the dice,
554
don't bother. Press @option{edit} and either type the @ref{What is a
555
position ID and match ID?,, position_id} and press @kbd{Enter}
556
on your keyboard. Or use the mouse to arrange the checkers.
558
Clicking the mouse on the border of the board removes all checkers. A
559
mouse click on a point then adds a certain number of checkers depending on
560
exactly where you click. For example, to add 5 men on your 6 point,
561
click at the top of your 6 point and it will fill with 5 men. The right mouse
562
button will add the men for your opponent's side. To add more than 5 checkers
563
to a point you need to further click on the bottom edge of the fifth checker.
564
Click on the the doubling cube to set its position and value.
566
Then go to the menu @option{Game, Set turn} and choose the player on
567
roll, the dice will then disappear.
569
@node How can I remove checkers from the bar?
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@subsection How can I remove checkers from the bar?
572
You can remove a chequer from the bar in edit mode by drag and drop
573
while holding down the [ctrl] key.
576
@node Which formats can I use to import positions?
577
@subsection Which formats can I use to import positions?
579
Currently only @file{*.pos} from @uref{http://jelly.effect.no/,,
580
Jellyfish} are supported.
582
@node Which formats can I use to import matches?
583
@subsection Which formats can I use to import matches?
585
You may import @file{*.mat} from @uref{http://jelly.effect.no/,,
586
Jellyfish}, @file{*.ssg} from @uref{http://www.gamesgrid.com/,,
587
Gamesgrid} or the @emph{oldmove} format used on
588
@uref{http://www.fibs.com,, FIBS}. Also possible now is the @file{*.tmg}
589
format of @uref{http://www.truemoneygames.com,, truemoneygames}.
591
@node How can I switch the players sides?
592
@subsection How can I switch the players sides?
594
Go to the menu @option{Game} and select @option{Swap players}.
596
@node What do "!" and "?" mean?
597
@subsection What do "!" and "?" mean?
599
After analysing a game or match GNU Backgammon lists some comments on
600
checker plays and cube decisions. Open the menu @option{Windows,
601
Game record} and you will see a list of moves. If any moves or cube
602
decisions differ from the best, GNU Backgammon will place a comment next
605
The default settings are:
607
@multitable @columnfractions .40 .30 .25
608
@item +0.040 (very good): @tab @emph{Not yet in use}
609
@item +0.020 (good): @tab @emph{Not yet in use}
610
@item -0.040 (doubtful): @tab @emph{?!}
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@item -0.080 (bad): @tab @emph{?}
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@item -0.160 (very bad): @tab @emph{??}
615
You may change these comments in the menu @option{Windows, Annotation},
616
creating other comments for moves and/or cube decisions.
618
@node How is the error rate determined?
619
@subsection How is the error rate determined?
621
GNU Backgammon determines the players strength as follows: If a player
622
has an average error (per move) of:
624
@multitable @columnfractions .40 .30 .25
625
@item Less than 0.005 ---> @tab @emph{Extra-terrestrial}
626
@item Less than 0.010 ---> @tab @emph{World class}
627
@item Less than 0.015 ---> @tab @emph{Expert}
628
@item Less than 0.020 ---> @tab @emph{Advanced}
629
@item Less than 0.025 ---> @tab @emph{Intermediate}
630
@item Less than 0.030 ---> @tab @emph{Novice}
631
@item More than 0.030 ---> @tab @emph{Beginner}
634
After analysing a game, match or session you can see a summary in the
635
menu @option{Analyse, @dots{} statistics}. Note that you cannot change the
636
ranges of these values.
638
@node Database questions
639
@section Database questions
642
* Which databases are available for GNU Backgammon?::
643
* How do I get these databases?::
644
* How do I create the bearoff databases?::
645
* How do I create the necessary databases for playing Hypergammon?::
648
@node Which databases are available for GNU Backgammon?
649
@subsection Which databases are available for GNU Backgammon?
650
Depending on the release and your settings there are different databases
653
@multitable @columnfractions .40 .30 .25
654
@item gnubg_os0.bd ---> @tab One sided bearoff database
655
@item gnubg_ts0.bd ---> @tab Two sided bearoff database
656
@item hyper1.bd ---> @tab Database for Hypergammon with one chequers
657
@item hyper2.bd ---> @tab Database for Hypergammon with two chequers
658
@item hyper3.bd ---> @tab Database for Hypergammon with three chequers
661
The default @file{gnubg_os0.bd} one sided bearoff database contains
662
the approximative probabilites for bearing off a maximum of 15 chequers on 6 points
663
in "n" rolls. The default @file{gnubg_ts0.bd} contains the exact probabilities for
664
a maximum of 6 chequers on 6 points for both sides. For a detailed desciption go to
665
Nardy's excellent page at @uref{http://users.skynet.be/bk228456/Bearoff-databases.html}
667
The @emph{Hypergammon} databases are for playing hypergammon. You have to create them
668
for your own. See @ref{How do I create the necessary databases for playing Hypergammon?}.
671
@node How do I get these databases?
672
@subsection How do I get these databases?
674
Actually the default databases (see above) should be included. For @emph{Linux systems}
675
you can also get them at @uref{http://www.acepoint.de/GnuBG/rpm.html}. The windows databases
676
can be found here: @uref{http://users.skynet.be/bk228456/dlls_recent_builds.htm}
678
@node How do I create the bearoff databases?
679
@subsection How do I create the bearoff databases?
681
Depending on your operating system it's either:
683
@command{makebearoff -o [P] -f [gnubg_os0.bd]} for @emph{linux} with "P"= Number of points
684
@command{makebearoff.exe -o [P] -f [gnubg_os0.bd]} for @emph{MS Windows}
688
@command{makebearoff -t [P]x[C] -f [gnubg_ts0.bd]} for @emph{linux}
689
with "P"= Number of points and "C"=Number of chequers
690
@command{makebearoff.exe -o [P]x[C] -f [gnubg_ts0.bd]} for @emph{MS Windows}.
692
Again a detailed description can be found at @uref{http://users.skynet.be/bk228456/Bearoff-databases.html}.
695
@node How do I create the necessary databases for playing Hypergammon?
696
@subsection How do I create the necessary databases for playing Hypergammon?
700
@command{makehyper -f hyper1.bd -c 1}
701
@command{makehyper -f hyper2.bd -c 2}
702
@command{makehyper -f hyper3.bd -c 3}
704
On @emph{MS Windows} it's
706
@command{makehyper.exe -f hyper1.bd -c 1}
707
@command{makehyper.exe -f hyper2.bd -c 2}
708
@command{makehyper.exe -f hyper3.bd -c 3}
710
Note that the 3-chequer database will need approximately 400 MB of RAM.
716
@section Abbreviations
729
"gwc" is an abbreviation for @emph{game winning chances}.
734
"mwc" is an abbreviation for @emph{match winning chances}.
739
In the menu @option{Analyse, Game/Match/Session statistics} you will see
740
a window with some statistics. Near the bottom are four lines beginning with
741
@option{Missed @dots{} and Wrong @dots{}}. "dp" means "doubling
742
point" and describes a situation in the game where you probably should've
743
doubled your opponent.
748
"tg" is an abbreviation for "too good". It indicates that you probably should have
749
kept the cube and not doubled (because of high gammon chances).
754
"Epc" is the abbreviation for "effective pip count". See @ref{Some Backgammon and technical
755
terms} for a detailed description.
758
@node Some Backgammon and technical terms
759
@section Some Backgammon and technical terms
762
* Effective Pipcount::
771
* Standard Deviation::
772
* Confidence Intervall::
773
* Joint Standard Deviation::
778
@node Effective Pipcount
779
@subsection Effective Pipcount
781
The @emph{effective pipcount} (epc) is the result of average rolls you need
782
to bearoff a chequer in a one chequer race muliplied with the average roll (8.167).
783
The @emph{wastage} is calculated as the result of epc - pipcount.
788
Player A: 5 chequers on his 1-point, 4 chequers on his 2-point
789
Pipcount: 5x1 + 4x2 = 13
790
Epc: 2.189 (Average rolls) x 8.167 = 17.878
791
Wasted: 17.878 - 13 = 4.878
794
It's easy to see that your wastage arises the more chequers you have on lower points (i.e.
795
you roll a 6 to bear off a man from the 2- or 1-point.
799
@subsection Kleinman Count
801
The @emph{Kleinman Count} is another calculation in longer bearoff situations.
802
The formula is DxD/S, where "D" is trailers pipcount + 4 - leaders pipcount, and
803
"S" is the sum of leaders and trailers pipcount -4.
805
If the result of DxD/S is round about 1.2, then the leader has a double and the
806
trailer a close take. Get more informations about the @emph{Kleinman Count} at
807
@uref{http://www.bkgm.com/rgb/rgb.cgi?menu+cubehandlinginraces}
811
@subsection Thorp Count
813
@emph{Thorp Count} is a mathematical method to calculate cube decisions in tricky
817
@item Count the leaders (L) and the trailers (T) pipcount.
818
@item Add an extra point for every checker on the acepoint (L1) and (T1).
819
@item Deduct an extra point for every possessed home board point (L2) and (T2).
820
@item Add two extra points for every remaining checker (L3) and (T3).
821
@item If the resulting leaders count (L3) equals 30 or is greater than 30 add 10% ((L4).
825
@item If (L4) - 2 equals (T3) it is an initial double and a take.
826
@item If (L4) - 1 equals (T3) it is a redouble and a take.
827
@item If (L4) + 2 is less than (T3) it is a pass.
830
Get more informations about @emph{Thorp Count} at
831
@uref{http://www.bkgm.com/rgb/rgb.cgi?menu+cubehandlinginraces}
834
@subsection Jacoby Rule
836
The @emph{Jacoby rule} is used in backgamon sessions or moneygame. This rule implies,
837
that a player can't win an undoubled gammon (meaning: when the cube is still in the middle).
838
This rule was established to protect players from "boring" games while watching his opponent
839
trying to win a gammon and getting doubled out if this doesn't succeed. For more information
840
see @uref{http://www.bkgm.com/glossary.html,, Backgammon Galore}.
844
@subsection Crawford Rule
846
The @emph{Crawford rule} is only used in match play. It implies, that a player cannot
847
double in the first game after his opponent has reached a score needing only 1
848
point to win the match. See also @uref{http://www.bkgm.com/glossary.html,,
854
A @emph{beaver} is only allowed in session games (also known as @emph{money
855
games}). To @emph{beaver} means redoubling (and keeping the cube) rather than
856
just accepting when your opponent has doubled (see
857
@uref{http://www.bkgm.com/glossary.html,, Backgammon Galore:
863
When you doubled your opponent, and he makes use of the @emph{beaver} you are allowed
864
to turn around the cube again. This is called a @emph{raccoon}.
868
@subsection Probability
870
The @emph{probability} describes the likelihood of an event's outcome. If you, i.e., flip
871
a coin the probability getting "head" will be 50% or 0.5 [going from 0-1]. Getting a certain
872
number on a die with numbers from one to six is 1/6 or 0.166 or 16%.
874
An example in backgammon:
876
Assume that you have one chequer on your 2-point and one on your 5-point. Your opponent has two
877
chequers on his acepoint, but fortunately you are on roll. What is your probability to win?
880
19 rolls (66, 65, 64, 63, 62, 55, 54, 53, 52, 44, 33, 22)
881
will take both chequers off, 17 rolls will not.
887
19/36 = 52,8% or 0.528
895
@emph{Equity} in backgammon is the number of points you expect to win in a certain position.
897
Take the same example from above. Your equity will be:
900
(19x1 (w) + 0x2 (g) + 0x3 (bg) - 17x1 (l) - 0x2 (lg) - 0x3 (lbg))/36
901
= 2/36 = 1/18 = 0.056.
904
Every time you play this position for a dollar you are expected to win 5.6 Cent. If you play
905
this position a hundred times your gain will be (theoretical) 5.6 dollar.
908
@node Standard Deviation
909
@subsection Standard Deviation
911
This is more difficult and best explained by an example. Let's assume you roll a die 10 times.
918
Add up all numbers and divide them by 10 (the number of rolls).
919
You'll then get an arithmetic mean of
925
Of course this differs from the expected value of
928
3.5 = (1 + 2 + 3 + 4 + 5 + 6)/6
931
The variance of our example is calculated as:
934
( (3-4)^2 + (6-4)^2 + (6-4)^2 + (1-4)^2 + (2-4)^2 +
935
+ (5-4)^2 + (4-4)^2 + (6-4)^2 + (5-4)^2 + (2-4)^2 )/10
937
= (1 + 4 + 4 + 9 + 4 + 1 + 0 + 4 + 1 + 4)/10 = 3.2
940
and is a measure for how far single events differ from the arithmetic mean. The standard deviation is the
941
square root of the variance, here it is
947
Transferred to our backgammon example from above let's assume you don't know anything about
948
the calculated probability we have done before (or imagine a position that can't be exactly
949
calculated). You play this position with a friend a hundred times, you win 58 games and loose
950
42 games. This will give you an equity of
956
But how sure can you be that 0.16 is the "true" equity of this position? Perhaps you will loose 6 points
957
in another session of 100 games. Let's calculate the standard deviation of our result.
964
@node Confidence Intervall
965
@subsection Confidence Intervall
970
@node Joint Standard Deviation
971
@subsection Joint Standard Deviation
977
@subsection Market Window
979
A @emph{market window} is the range between the point of "first double" and
980
"last take". In moneygames it's usually between 50% - 75% winning chances
981
depending on the value of the cube. In matches this range may extremely differ.
985
@subsection Gammon Value
986
In money games the @emph{gammon value} is usually 0.5. This means that you have
987
to win twice as much gammons than loosing games to justify a certain move
988
compared to another candidat. In matches this may also extremely differ depending
added
removed
doc/faq.texi
