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Subject: Re: Strange error in Hiarcs 7.32 game

Author: karen Dall Lynn

Date: 05:58:34 02/01/02

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On February 01, 2002 at 02:44:18, Mike Hood wrote:

>I'm posting the whole game of an engine-engine match I played on my PC. White
>was Hiarcs 7.32, Black was Chess Tiger 14.0, both were using 128 MB Ram. The
>time conrol was 40'/40+40'/40+40'
>
>The strange move is move 121. The position looks to me like a drawn game. Hiarcs
>thought for 25 seconds to a search depth 13, evaluated Ka6 as 0.0, made his
>move, and oops! -- he'd overlooked a mate in 1.
>
>I've tried duplicating this error in vain. In analysis mode Hiarcs sees the
>Mate. Has anyone else noticed similar things happening with Hiarcs?
>
>---
>
>[Event "Strange Hiarcs Error"]


This error is a particular instance of a more general error: that of the
dramatic change in evaluation following a move alredy done. Worse: for some bad
moves, sometimes the dramatic change comes only a little after you force the
move. If you undo the move evaluations reset to their anterior state in which
the move is unsuspicious, but after forcing the same move again a big change is
seen again - and we ask ourselves how and why the brainy engine did not see the
flaw coming while it was a move back and in time to avoid it. May this change be
for green-up or for red-down arrows, chess programs really do that sometimes,
but only rarely they engage in a blunder that is just passing by the analysis
stream.

It means that proficient computer chess playing should not relax the need of
chess knowledge for the human operator - I learned from a friend with a GM
profile that sometimes (mainly in the openings) forcing/refusing moves in the
light of human experience improves the computer further conditional choices.

I have experienced once, with Fritz 6, an useless Queen sacrifice followed by a
resign 10 moves ahead. Your case is still more fascinating, since an 1 move mate
was overlooked - treasure it, it is a pearl and a very rare blunder against our
friends automata.

Karen




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