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Subject: Re: So how do we tell when to avoid null-move?

Author: Heiner Marxen

Date: 09:09:10 11/06/99

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On November 05, 1999 at 12:48:25, Dann Corbit wrote:

>On November 05, 1999 at 12:39:20, David Eppstein wrote:
>>This and the many other null-move-killer positions regularly posted here seem to
>>show that crafty's simplistic check (avoid null move when side to move has only
>>one non-queen piece) could stand some improvement.  What better algorithms are
>>other programs using to tell when a position might be zugzwang?  I vaguely
>>remember a commercial programmer (Christophe or Ed?) making a cryptic comment
>>about double-null-move solving this problem, but I didn't understand what that
>>might mean.
>For a multi-threaded chess engine, why not have additional threads doing other
>tasks.  If (for instance) you had a 32 CPU machine, it seems that one thread
>running with null move off and one thread running as a mate solver would be a
>good idea.

The problem here usually is not to run other (sub-)tasks, but to interpret
their result.  Assume the non-null thread delivering some different result.
But then, it was just one thread, instead of those many other ones.
Is the result really more reliable?  If so, why didn't you do it that way
from the start?  I donīt see easy answers, here.

OTOH, a mate result is always directly interpretable.


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