Author: Robert Hyatt
Date: 18:42:32 01/30/01
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On January 30, 2001 at 14:03:21, Olaf Jenkner wrote: >> >>There are three easy ways to tone crafty down: >> >>1. use the "extension" command to reduce or completely disable the various >>search extensions. This will make it less tactically "aware". >> >>2. turn off null-move completely. >> >>3. use the "evaluation" command to scale some of the 'knowledge' back. IE >>reduce things like pawn structure, passed pawns, king safety, and so forth. >> >>If you find something you like, setting wise, send it to me and I will add >>a "personality" feature to make it easy to invoke your settings... > >I think thats not the way of humans weak playing. >If you scale 'knowledge' back, a human can use this and play better. However, this is what weak humans do. They are worse at tactics than a strong player. They also know less about positional concepts. IE weak pawns, strong pawns, good space, bad space, king safety, endgame potential, you-name-it. A chess engine has several things: 1. opening book. You can make it weaker by letting it play lines that a strong player would never consider. This can be done by simply increasing the "width" to let more book moves into the decision process, and then using more randomness rather than using features like frequency and learned results to choose the final move played. 2. tactics. This is the hardest part of the engine to tone down. A good alpha/beta search is still very strong, even with all search extensions turned down to zero. But by turning them down low, and even disabling null-move which will further reduce the depth, what you get is a player that will never make a 2-3-4 ply mistake, but it will definitely fall into deeper traps. That is not the way a 1500 player plays, usually. 3. knowledge. Programs are getting pretty sophisticated here. Turning off parts of the evaluation can weaken the engine in a natural way. Beginning players aren't going to think much about majorities, mobile majorities, fixed majorities, etc. Everybody knows to not put th eknight on the edge of the board, probably. But not everybody knows about a 3-2 queenside majority. Ditto for king safety. As these get turned down, it will get dumber. The real problem is the tactics. Some have gone so far as to invert king safety values in Crafty, so that it tries to shred its own king-side rather than protect the pawns there. That is the extreme end of dumbing-down, probably. I suspect that a material-only program will still be a non-weak opponent... >If you reduce extensions the human can use horizon effect. >A downscaled chess programm should 'oversee' some things. I mean >it should do a normal search but randomcally make mistakes. For instance >to forget a hanging peace. >I don't know if commercial programs have a such approach, >I think but it would be nice. > adding a bit of randomness is doable. It is not trivial due to the effect of the hash table. But it is doable. >Olaf Jenkner
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