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From: | Ian Shaw |
Subject: | RE: GNU Backgammon Clones |
Date: | Wed, 23 Jun 2021 08:45:47 +0000 |
Hi Jeurgen,
The techniques for creating a strong backgammon program are well known, and any strong bot is going to make the same move as another
strong bot, simply because it is the correct move. The main way to demonstrate that the nets are identical is to show that they make the same move in all circumstances. This is complicated
by the fact that the net can be set with various evaluation parameters so that the same network will make different moves, depending on the search depth, move-pruning settings and so on.
I’m afraid I can’t help with getting hold of old versions. Perhaps some of the developers would know if they are somewhere in the depository. What is the problem you are trying to solve? Gnubg is an open source program, so people are allowed to take it and use it as they like,
even to the point to selling it. However, they would be breaching the licence if they didn’t include the gnu licence in their software and make the source code available. Is this your concern.
Regards,
n
Ian Shaw From: Bug-gnubg [mailto:bug-gnubg-bounces+ian.shaw=riverauto.co.uk@gnu.org]
On Behalf Of Juergen Schaefer Hi ! GNU Backgammon Clones It's a very "sensitive theme" and a difficult problem: cloning. Is it possible to track down, to prove that a certain program is a clone of GNU Backgammon ? Since about 20 years there are some programs commercially available (by the same author)... frankly spoken I believe that all these programs are not driven by an original engine, We have only the source code of one program (GNUBG) - a direct comparison isn't possible. So I can only try to collect circumstantial evidence instead. GNUBG started in 1999, shortly afterwards (about 2001) the first suspected program was on the market. The features of the "clones" are very similar to GNUBG's - the playing strength also.
For example there is a serious bug in the move generator, a "clone" doesn't accept a possible move while bearing off !! "Clone" Opponent pip count 87:27 Opponent rolls 5+3 - the (best) legal move 6/3 4/off isn't shown respectively Really bad for a program that plays at world class level ! GNUBG has 5 main levels: Might happen by accident that the "clone programs" also always have 5 levels. But how about the "treacherous" beaver feature: How many programs do you know which have implemented the option beaver The "clones" use another dice generator which appearantly isn't working very well: The identical games were played the same day within a few hours...the dice
I think all "clone programs" are neural nets like GNUBG - not only like GNUBG,
nor weight files. Probably incorporated directly into the exe-files which are quite large (about 4 MB) ?! I am convinced that none of the "clone programs" will be better than GNUBG Just another question about the similarity of GNUBG and the "clone programs": How about GNUBG (around 2000) ? The simple move generator bug in the GUI, which doesn't allow a legal move, Additionally the autor has cloned his "own" program and sold under another label Never heard of the author of the "clones" before - out of the box with world I doubt - but it is still only an initial suspicion, possibly well founded, At the moment I am collecting blunders of the "clone programs" then I would Do you know if it is still possible to download very old versions of GNUBG Seems to be the only chance to prove vast similarity...that will be tough, These two elementary features never implemented in the last 20 years...why ? These "clone programs" definitely need further investigation.. . Do you have any idea what can be done in order to prove or to refute my suspicion ? All these points above leave a bad gut feeling to me. Am I on the right track ?
Any hint, any help much appreciated ! Thank you very much !
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