Author: Sergei S. Markoff
Date: 10:39:07 09/18/02
Hello all! It's surprise for me that PASSED_PAWN_PUSH extension is off in SmarThink since 0.00a!!! Anyway SmarThink is playing OK!? Is it means that PASSED_PAWN_PUSH extension is not such imortant or it means than SmarThink is really much stronger than now? It is also interesting term to discuss: how PPP-extension must work. I think that Crafty's (and also SmarThink's and others scheme) is not quite well. I think that it is possible to enlarge search depth not only for pushing pawn to 7th (2th) rank but also for other pushing when result of SEE for this move is not pawn losing... But I'm don't know the optimal extension value. May be it's about 1/2 ply for 6th rank and 1/4 ply for 5th rank? PPP-extension must resolve two type of problems: 1) we can't see the losing of pushed pawn 2) we can't see the promotion But the probability of existing (1) and (2) are the different because of some properties of eval. function. "Evaluate" _want_ to push pawn. And that's why (1) is more important than (2). Losing of our passed pawn for engine is much terrible than no promotion. Because of losing game is worse than not winning. I think that it's ideas can be used in creating good non-Crafty scheme of PPP-extension. Sincerelly yours, Sergei
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