Author: Brian Richardson
Date: 05:07:36 08/26/04
Go up one level in this thread
On August 25, 2004 at 23:51:50, Stuart Cracraft wrote: >On August 25, 2004 at 12:58:23, Brian Richardson wrote: > >>On August 25, 2004 at 12:42:34, Volker Böhm wrote: >> >>> >>>Hi, >>> >>>the following position of the iq - test (position 166) cannot be solved from >>>spike in reasonalbe time (> 2h): >>> >>>r4r1k/6pp/3p3b/1p1Npb2/3nB2q/2N3P1/PP3P1P/R2Q1RK1 b - - 0 1 >>> >>>(The Move is Qxe4) >>> >>>The reason is a nullmove-problem. After the queen-sac there are many moves that >>>leads to a mate-thread. But one queen back spike tends to prune because of >>>nullmove result (one move is not enough to show the mate thread thus going back >>>to window). >>> >>>I tested the position with fritz 8, he solves it in 8 ply in nearly no time. >>>Are there non commercial engines that solves this position too in a short amount >>>of time? >>>Maybe the author of this engine would be so kind to explain the rule that solves >>>the nullmove-problem. >>> >>>Thanks Volker >> >>I have two versions of Tinker that I have been experimenting with for some time. >> One is "regular" Tinker with full evaluation, and the other uses only pawn >>evaluation and some simple PCSQ terms (e.g., no king safety, etc). The search >>is the same in both versions. Regular Tinker solves this in a few seconds at 8 >>ply, and the "simple" Tinker does not after a long time. I suspect the >>difference is the king safety and not so much null move or pruning, at least for >>Tinker (which would normally lose to Spike anyway). >>Brian > >Can you be more specific about regular Tinker's king safety? What specifically >does it have? > >Stuart Like most programs, Tinker has quite a few king related evaluation terms, some of which depend on the game phase and where the king is, and are scaled by opponent material, and some are asymmetric. In addition to piece square tables there are penalties for controlling squares around the king. This is one area that I am constantly tinkering with. The following should give you an idea: #define KING_EARLY_PIECES #define KING_MOVED_EARLY_PENALTY #define KING_MOVED_PENALTY #define KING_FILE_OPEN_PENALTY #define KING_XRAY_BONUS #define KING_PIN_BONUS #define KING_PAWN_MOVED_PENALTY #define KING_AH_NOPAWN_PENALTY #define KING_AH_ATTACK_PENALTY #define KING_AH_OPEN_PENALTY #define KING_PAWN_COVER_BONUS #define KING_QUAD_PENALTY #define KING_ZONE_PENALTY #define KING_ATTACK_PENALTY #define KING_FIANCHETTO_BONUS #define KING_KINGSIDE_PAWN_BONUS #define KING_QUEENSIDE_PAWN_BONUS #define KING_CASTLED_PAWN_BONUS #define KING_QUEEN_FLANK_PENALTY #define KING_CENTER_PENALTY #define CASTLE_SCORE Brian
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