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Subject: Re: Explosion in WAC 102

Author: José Carlos

Date: 09:28:56 01/11/02

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On January 11, 2002 at 12:10:32, Martin Giepmans wrote:

>On January 11, 2002 at 11:44:39, David Rasmussen wrote:
>
>>[D]2Q2n2/2R4p/1p1qpp1k/8/3P3P/3B2P1/5PK1/r7 w - - 0 1
>>
>>In the above position, my search tree explodes because of extensions. It takes >
>>3 minutes and 42 million nodes to finish an 8 ply search. How does your program
>>do?
>>
>>Any good ideas on how to limit extensions in such a position.
>>
>>P.S. Solving the position is no problem. It is a simple mate in 5 plies, and is
>>found very early on at depth 1 or 2 or so. Still, there must be something
>>unsound about my extensions, or at least room for improvement, when this
>>position makes the tree explode.
>>
>>/David
>
>I don't know if I understand your question.
>How can you reach depth 8 when a mate is found at depth 1 or 2?
>Doesn't your engine stop in such a case?
>Even if you want to look for a shorter mate, searching *deeper* is of course
>useless ...

  That's wrong. You can find a mate in 5 at depth 2, but you can't be sure there
isn't a shorter mate until you finish ply 9, supposed you don't do some risky
prunning. If you do null move, for example, you may need to search beyond that
to find a shorter mate.

  José C.

>Anyway, if the search explodes after a mate is found, I guess there must also be
>something wrong with the hashtable.
>
>Martin



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