Yeah! Good points, Ian. Maybe it is possible to "reverse engineer" the executable code of the potential clones and see if it matches the weights of a neural network from GNU Backgammon. The weights of a neural network will indeed be sequential in memory as in GNU Backgammon. This will be strong enough prof to bust someone. THat is a much stronger prof than vaguely claiming they play the same moves. However, these take competence of decomiling and investigation of windows executables. (A competence I do not have, but may be able to learn)
However: What do we intend to do if we can confirm that these are real clones? I guess the "author" doesn't make a lot of dough from his sales? -Øystein On Wed, Jun 23, 2021 at 10:46 AM Ian Shaw <[email protected]> wrote: > 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= > [email protected]] *On Behalf Of *Juergen Schaefer > *Sent:* 22 June 2021 22:35 > *To:* [email protected] > *Subject:* GNU Backgammon Clones > > > > 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, > but their evaluation engines are based on GNU Backgammon. > IMHO in fact it's GNUBG in disguise, simply put: clones. > > > > 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. > Until now there are at least 6 of them published by the same author. > > > > The features of the "clones" are very similar to GNUBG's - the playing > strength also. > > > Whereas the GUI of the "clones" is "shaky", almost clumsy. > > > > 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 > Bar 1x 1 3x > 9 1x 2 2x > 18 2x 3 2x > 20 3x 4 2x > 22 3x 6 1x > 23 3x ab 5x > 24 2x > > Opponent rolls 5+3 - the (best) legal move 6/3 4/off isn't shown > respectively > won`t be accepted at all by the "clone" GUI, the "clone program" accepts > only > 6/1 3/off and 6/1 4/1 !! > > > > Really bad for a program that plays at world class level ! > > > > GNUBG has 5 main levels: > 1. World class > 2. Expert > 3. Advanced > 4. Intermediate > 5. Beginner > > > > Might happen by accident that the "clone programs" also always have 5 > levels. > > > > But how about the "treacherous" beaver feature: > beavers are not part of the official backgammon rules - so why bother with > this superfluous stuff ? > > > > How many programs do you know which have implemented the option beaver > being open source - exactly one, GNUBG - who else ? > > > > The "clones" use another dice generator which appearantly isn't working > very well: > 2 identical games within a few hours with 8 moves respectively 36 moves > each. > How likely is that ? > > > > The identical games were played the same day within a few hours...the dice > generator of the "clones" seems to work quite odd...doesn't it ? > > > Repeating dice numbers within such a short period - Mersenne Twister > provides > better randomness. > > > > I think all "clone programs" are neural nets like GNUBG - not only like > GNUBG, > IMHO GNUBG based. > > > Although at first sight it might look like that these programs have no > bearoff database > > 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 > of that corrrespondent time, perhaps a few elo points less. > > > > Just another question about the similarity of GNUBG and the "clone > programs": > not in the shareware versions, but in the full versions of the "clones" > there is a possibility to play over network, TCP/IP port. > > How about GNUBG (around 2000) ? > > > > The simple move generator bug in the GUI, which doesn't allow a legal move, > the lousy random generator and the missing possibilities of entering > positions > and manual dice - this doesn't really fit together to the world class > engine. > IMHO clear indications for cloning. > > > > Additionally the autor has cloned his "own" program and sold under another > label > exactly the same...- the versions from 2003 and 2005 are absolutely > identical, > even the readme-file ! Ok...name and package were new...!! > > > > Never heard of the author of the "clones" before - out of the box with > world > class performance, absolutely brillant...not bad for a newcomer program - > but is it really a program written from scratch ? > > > > I doubt - but it is still only an initial suspicion, possibly well founded, > but still no clear evidence. Definitely no final judgement. > > > > At the moment I am collecting blunders of the "clone programs" then I would > like to do a "cross blundercheck" with GNUBG versions around the year 2000 > . > > > > Do you know if it is still possible to download very old versions of GNUBG > v. < 0.10, 1999-2000 ? > > > > Seems to be the only chance to prove vast similarity...that will be tough, > as the "clones" do not provide the possibility to enter positions, > also manual dice entry is missing in all "clone programs". > > > > These two elementary features never implemented in the last 20 years...why > ? > Of course it's more difficult to reproduce, to compare games... > > > > 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 ? > Or is my clone suspicion just clueless ? > > > For me it isn`t easy to verify if it's a clone or not - might be the > experts can ?! > > > > Any hint, any help much appreciated ! > > Thank you very much ! > > > >
