Author: Tim Foden
Date: 04:58:50 09/18/03
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On September 18, 2003 at 06:29:03, macaroni wrote: >How much searchdepth is it worth giving up for a stronger evaluation function? I >often find, that while my program is playing GNUCHESS, or AnMon, both the other >computers give a reasonable + score in a position in which neither side is up a >pawn (and neither side will be in the ply 8 searches they are managing). My >almost entirly tactically based program gives a slightly worse score, and loses >20 moves later (the position being dead lost the whole way). But lets say, I >code a much better eval function, and as a result, lose about 1 ply. Is it worth >it? or does the extra ply really count heaps. It can be worth it. It depends on how much evaluation you already have. I did an experiment once... I made a version of GLC 2.18 that used only material balance in its evaluation. It played a 20 game match against GLC 2.13. During the match 2.18 averaged 2 to 4 ply more than 2.13 (mainly due to extra cut-offs, the NPS search speed was only about 20% faster). The result... 2.13 won, by 19.5 points to 0.5 points. This gives roughly a 640 ELO rating difference. Normally I would expect 2.18 to be about 50 ELO stronger than 2.13. So loosing the 'positional' part of the eval function seems to have caused around a 700 ELO drop in strength. Conclusion: the evaluation is important. :) > > >[D]2r5/1b2k1p1/p2pp2p/4n3/1pP1P3/8/P1PNB1PP/2K2R2 b - - 0 22
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