Author: Bruce Moreland
Date: 21:25:59 06/23/98
Go up one level in this thread
I trimmed too many header thingies, the following is Don talking: >>I have some doubt as to whether implementing the 50 move rule in the >>search will help in a very noticable way. It's extremely rare that the >>program is in a 50 move situation AND a won position (which it can >>not win) simultaneously. The 50 move rule does not even guarantee >>the win in a won situation, it just makes a win (and a loss) somewhat >>more likely. I have seen it happen that other programs give up material >>to avoid a draw which causes it to lose. Something under 2% of my ICC games against the strongest players (IM, GM, others rated >= 2400, which is most computers) end as 50-move draws. Which is not to say that the 50-move rule is important in only these games, I have other games that get close to 50 and are drawn by insufficient material or repetition, and I get some others where I might avoid the 50-move draw by moving a pawn, and then the game goes onto some other conclusion. The most typical case, based upon no numbers but a lot of watching, is that the program sees the 50-move case coming, but sees it too late to do anything about it, and so the game ends up being drawn anyway. I don't recall a case where it gave up material to avoid the 50-move rule and lost, but it sounds more familiar that I've seen it go the other way, where someone else did this against me and lost. I'm sure that there have been cases where the program was inspired to do something by the approach of the 50-move limit, and won the game, but I can't recall a specific instance, and I know that I've seen a lot where I've gone "damn" and taken the half-point. A few where I've felt that had the program seen it coming sooner, that it could have been in position to make an effective pawn break. If you have pawns, and they can do something productive, they tend to advance, which removes the need to care about the 50-move rule. If you don't have pawns, the odds that you can win a pawnless ending by making an opportune trade are very low, I think. >>What is the general feeling on this? Does anyone feel it adds more >>than 1 rating point to the program? If it adds more than 1 rating >>point I might consider putting it in Cilkchess if the slowdown is >>less than 1 percent (which would approximately cancel the improvement.) Good question, I don't know. I never bothered to ask this question, I just implemented the 50-move rule without thinking about it. >>I have never played a tournament game where any of my programs were >>ever in this situation and lost a half point for not getting desparate >>to avoid the draw although I realize this is always a possibility. >>I have seen it happen in test games, always on super fast levels like >>1 or 2 ply searches. In some of these situations it was just a >>technique problem and pawn moves or captures were not involved, it >>just couldn't win knight and bishop vs king or some other difficult >>ending. If I could give you a pill that would cause you to do one thing of my choosing, I would give you a pill that got you on ICC or some other server. I would like to see your program play, I would like to test it with my own program, and others would, too. The up-side for you is that you get a lot of games of varying degrees of quality and against various types of opponent in your email, and you can go through them and sometimes find problems and other interesting cases. bruce
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