Author: Enrique Irazoqui
Date: 15:00:48 01/13/99
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On January 13, 1999 at 17:10:18, Robert Hyatt wrote: >On January 13, 1999 at 01:41:36, blass uri wrote: > >>I am sure that crafty could not use tablebases in the way it knows (otherwise >>it would not go for a lost KRP vs KR and understand only after trading rooks >>that it is losing) >> >>Another question: >>Did you tell crafty that it is playing a computer opponent. >> >>In the following position against hiarcs7(game 180) >>crafty's evaluation was 0.33 >>4rk2/5R1R/1P6/P1p5/3r3P/8/6PK/3q4 b - - 0 1 >> >>I found it strange because it is an obvious draw. >> >>I tried crafty15.18 as an engine for fritz5 and if I tell it computer opponent >>the evaluation becomes 0. >> >>If I give it human opponent in the engine parameters then the evaluation in the >>game is 0.33 advantage for white. >>and if I give it as a position without a game the evaluation againsta human >>opponent is 0.66 >> >>Uri > >Good eyes. I've mentioned this before, that Crafty has a "dynamic draw score" >that varies from -1.00 to 0.00 depending on the phase of the game. This is to >discourage going for a draw in an opening where it gambited a pawn, or in a >middlegame that is pretty even, because it has good tactical skills that might >win. > >A draw score of .33 (for white) must mean crafty was black and it saw a >draw... which is not good against computers, because it means that Crafty >will totally wreck its position to avoid a draw against a very strong opponent. > >I have some patches I did for xboard (and sent them to Tim Mann) which recognize >computer opponents on the chess server and send the command "computer" to >crafty. This forces it to use the normal draw score which should be 0.00 for >most cases, unless the computer is higher rated, where it uses +.2 since a draw >is a good result. > >Hopefully this isn't happening in this tournament, however, and maybe I am going >to make this draw score stuff disabled by default and only turn it on when >running on the chess servers against humans... look for that in 16.4. :) So we have another bug in Crafty 16.1 for Fritz. Before the first match, I went to “Engine parameters”, unchecked “No tricks”, checked “Draw normal” and then clicked on Save. I looked at it just now and parameters are not saved at all, which means “Tricks” are on and “Draw normal” off unless this is modified every time Crafty is loaded... Same for 16.3, by the way. Enrique
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