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Subject: Re: Crafty questions

Author: Robert Hyatt

Date: 09:15:51 08/04/05

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On August 04, 2005 at 11:16:55, Kevin K wrote:

>Hello, Dr. Hyatt.
>
>My question is about easy move in root.c:
>
>  if (sort_value[0] > sort_value[1] + 200 &&
>      ((To(rmoves[0]) == To(last_opponent_move) &&
>              Captured(rmoves[0]) == Piece(last_opponent_move)) ||
>          sort_value[0] < PAWN_VALUE)) <------ ?
>    easy_move = 1;
>
>I understand recapture is easy move.
>But, I don't understand why if sort_value[0] < PAWN_VALUE, it is easy move.

Suppose your opponent appears to hang a piece out of the blue.  That is, your
last search produced a score of +.2, and then you made that move.  When your
opponent makes a move, and you start off with a score of +2, do you believe that
he hung a piece, or perhaps the piece is "poisoned"?  Here is a position from
Cray Blitz vs Belle, ACM 1981, that illustrates the problem.  Qxb6 loses badly.
Yet it appears to win material to a very shallow search.

5r1k/6p/1n2Q2p/4p//7P/PP4PK/R1B1q/ w - - 0 1

the above simply says "if the score is significantly plus, I'm going to be
suspicious that my opponent is not that stupid, and use all the time in case it
is a trap...




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