Author: Don Dailey
Date: 14:05:13 01/02/98
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On January 02, 1998 at 16:20:29, Amir Ban wrote: >On January 02, 1998 at 14:59:02, Don Dailey wrote: > >>On January 02, 1998 at 14:03:48, Stuart Cracraft wrote: >> >>>Perhaps not directly related but I'll share this anyway... >>>My experience in adding knowledge to the evaluation function >>>and its relation to test results is that pure tests like >>>Win-at-Chess and other tactically-based tests, including >>>rating tests that are more tactical (like Kaufman's) suffer for >>>more evaluation knowledge but that non-tactical tests may benefit. >>> >>>A recent result was that correcting some pawn structure logic >>>in a program that was mis-evaluating passed/doubled/isolated >>>pawns dropped the Win-at-Chess score by about 2.66% in total >>>problems solved but raised the Louguet rating by 45 ELO points. >>>At the same time the Louguet result went up 45 points the >>>Kaufman result went down 24 points. >>> > >You were almost certainly looking at random noise. In a 300 position >test-suite, I can get the SAME program scoring 3-6 less on its "bad" >day. Test suites like Louguet are so small that no real significance >should be attributed to any particular result. Understanding the effects >of noise is the key to keeping your sanity in this business. Controlling >it is a different question. > > >>>This result came by making only these changes: >>> 1. correctly evaluate passed pawns based on rank >>> (previously, no passed pawn logic) > >An important change for endgames, but cerainly not for the WAC suite. > > >>> 2. correctly evaluate doubled pawns >>> (previously, penalized 2 pawns on file, but ignored more than 2) > >Isn't this totally insignificant ? > > >>> 3. correctly evaluate isolated pawns based on file >>> (previously did not take file into account.) >>> > >What's the correct evaluation of isolated pawns based on file ? > >Amir He is a thought on the isolated pawn thing. Like any pawn structure thing a good program will have different values depending on file and rank. For instance a backward 'a' pawn is not nearly as serious as a backward d or e pawn. -- Don
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