Author: Robert Hyatt
Date: 10:26:43 02/04/03
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On February 04, 2003 at 08:37:57, Jarkko Pesonen wrote: >[D] 4k2r/3p4/p3pQ2/6P1/1pq5/7r/PP6/R1KN1R2 w > >This is draw , but how do you statically can evaluate that it so? > >This was the quiescent position and crafty suggested Nc3 bxc3 and not go for >repetion(eval 0.09 for crafty statically after these moves but search from this >position reveals that this loses rook at lest ) and ruffian correctly wanted to >play Kb1 which was the repeating move. > > >Anyway ruffian seems to find drawing lines much sooner than crafty. >Does anyone have a glue why it is so fast. >It catches draw a few ply earlier than crafty. >Is there a way fix this in crafty? > > >Jarkko You are probably mis-interpreting the concept of "draw". For a program to see a draw by repetition, two things have to happen: 1. It has to believe that one side can _force_ the repetition, if the other side plays in a particular way. 2. It has to believe that the other side would be worse off it it tries to avoid the repetition. All you need in a position like this is to think that one side is is better than the other, and you might or might not be able to see the repetition. IF one program thinks white is slightly better, then it would think that black would try to force the repetition and white must go along or else get "worse". If another program thinks black is better, then it might totally ignore the repetition opportunity. Usually one side has the option to vary, say in a perpetual check the checking side doesn't have to check. But he has to believe that if he doesn't check, the opponent has a better resulting position. If that is not true, the perpetual won't be played.
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