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Subject: Re: Strange error in Hiarcs 7.32 game

Author: Uri Blass

Date: 07:50:14 02/01/02

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On February 01, 2002 at 10:36:54, Mike Hood wrote:

>On February 01, 2002 at 05:49:48, Kurt Utzinger wrote:
>
>[White "Hiarcs 7.32"]
>[Black "Chess Tiger 14.0"]
>
>[D] 8/8/K1kn2R1/8/P6r/8/8/8 b - - 0 1
>
>121. Ka6??
>121... Rxa4#
>
>>Such error happens from time to time in computer games and are the exception of
>>the rule. And it is clear: nobody will ever be able to reproduce the situation.
>>Kurt
>
>I agree.
>
>It's obviously a problem of selectivity, somewhere along the line. The very
>first chess programs relied on brute force to analyse all possible
>continuations, but today's chess programs have only become stronger by deciding
>what NOT to analyse. All the same, in the above position I have to naively ask,
>"Shouldn't a program at least do a 2-ply exhaustive search from the root?" (Or
>is it 3-ply, to recognize that there are no legal replies to Rxa4?) Missing a
>forced mate in 4 is something that might happen to me on a bad day, but this
>example is a blunder that only a beginner would make.
>
>It seems to me that this is a special position. Hiarcs is obviously fighting to
>avoid a draw by the 50-move rule. (See my original post: a4 in move 111 is
>already the 42nd move according to the rule).
>
>But just think of the implications if this hadn't happened in an obscure
>engine-engine game. Just imagine if Black's name were not "Chess Tiger" but
>"Kramnik". Instead of this small discussion (which will probably die out after a
>few replies) it would be a matter of heated argument for months. It wouldn't
>just reflect on Mark. Every computer chess programmer would be up against the
>wall. The boulevard press would be less kind than we are in here. Just imagine
>the headline: "After 40 years of research computer chess still sucks"
>
>I'm not a journalist, so I won't speak those words myself :) All I can say is
>that this is a strange curiosity, and I hope I won't see it again.

I suspect that only hiarcs can blunder like this.
This program simply have bugs.

I already found strange tactcial errors with hiarcs when it did not happen with
other programs.

There are cases when I could reproduce the errors if I gave hiarcs to play the
same game again but could not reproduce the errors when I gave Hiarcs only to
play the same position again.

I believe that it has some bug in retaining the hash tables

Uri



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