Author: Uri Blass
Date: 06:40:41 03/12/02
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On March 12, 2002 at 08:40:28, Chessfun wrote: > >What are the differences in Crafty 18.13 compared to 18.12? 6 differences from Crafty's source code(I guess that 1 and 6 are the most important changes): The following was copied from main.c in crafty source code and I only edited it by adding a number for every change: 1)Deep Blue extension limit removed and restored to one ply of extension per ply of search. 2)pruning in q-search fixed so that a capture will be considered if it takes the total material on the board down to a bishop or less for the opponent, as that can greatly influence the evaluation with the EvaluateWinner() code. 3)as the 50 move rule draws near, the hash table scores are marked as invalid every 5 moves so that hashing can't hide potential 50-move-rule draws. 4)lazy evaluation code modified to be more conservative, since in endgames the positional score can be a large change. 5)EvaluatePassedPawnRaces() fixed so that if one side has two pawns that are far enough apart, it will recognize that even though the king is "in the square" of either, it can't always stay in the square of one if it has to capture the other. 6)pawn hash signature restored to 64 bits after testing proved that 32 was producing an unacceptable number of collisions. search node counter is now 64 bits as well to avoid overflows. but in the outside passed pawn code fixed (bad mask). Uri
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