Author: Robert Hyatt
Date: 14:45:11 01/02/98
Go up one level in this thread
On January 02, 1998 at 17:05:13, Don Dailey wrote: >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 I'm not sure I agree with this. Generally an isolated pawn on the edge is not quite as bad as one in the middle, because it can only be attacked from the front/back and one side, rather than both sides. but I've lost plenty of games from a weak a pawn. (weak = isolated, backward, and so forth).. I think the file is less important than other things about the pawn... ie is the file half-open and does the opponent have rooks to attack down that file? etc...
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