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Subject: To Dr. Hyatt (bug in Crafty?)

Author: Sergei S. Markoff

Date: 12:04:19 10/16/02


Hello Robert!

Sorry for my penetration, but because I'm trying to be well in computer chess I
must know all about Crafty from line #1 to the end (:

========= Crafty 19.0, evaluate.c, from line #133 ===========
    if (wfile+wtm > bfile+1) {
      if (wfile < FirstOne8Bit(tree->pawn_score.allb))
        pscore+=WON_KP_ENDING;
    }
    else if (wfile-wtm < bfile-1) {
      if (wfile > LastOne8Bit(tree->pawn_score.allb))
        pscore+=WON_KP_ENDING;
    }
    if (bfile > wfile+1-wtm) { // must be "(bfile > wfile+1-!wtm)" ??
      if (bfile < FirstOne8Bit(tree->pawn_score.allw))
        pscore+=-WON_KP_ENDING;
    }
    else if (bfile < wfile-1+wtm) { // must be "(bfile < wfile-1+!wtm)" ??
      if (bfile > LastOne8Bit(tree->pawn_score.allw))
        pscore+=-WON_KP_ENDING;
    }
=============================================================

Strange assymmetric evaluation for black/white. See my comments in listed
fragment.

Sincerelly yours,
Sergei

P.S. Why Crafty is still not using (ext-d) futility pruning / razoring?
P.P.S. I'm not supports your optimism about new extension limitation scheme, my
test shows that old scheme is better... But I may be wrong.




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