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Subject: Re: To check or not to check, this is the quiescence question

Author: Uri Blass

Date: 06:47:39 10/12/03

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On October 12, 2003 at 09:27:09, Tord Romstad wrote:

>On October 12, 2003 at 06:32:25, Omid David Tabibi wrote:
>
>>Recently I conducted some extensive experiments with two versions of Falcon, one
>>with checks in quiescence and one without. Falcon already has lots of
>>extensions, but adding checks in quiescence resulted in a significant boost for
>>tactical strength.
>>
>>I tested the following options:
>>
>>a) checks everywhere in quiescence
>>b) checks only in the first ply of quiescence
>>c) no checks in quiescence
>>
>>Option 'a' was ruled out after some testing, as it resulted in a total explosion
>>of quiescence search. I tried controlling it in some ways, but still the
>>overhead was considerably more than the benefit. It seems that The King and
>>HIARCS are the only engines using this method.
>
>These are not the only ones.  I am fairly sure Diep searches checks everywhere
>in the
>qsearch, and Gothmog (my engine) also does.


If you searches checks every where in the search then by definition
you find the draw at ply 1 if your program has stalemate detection in its
evaluation.

[D]r7/8/8/8/8/PPPP4/2QP4/k6K b - - 0 1

If it does not detect the draw at depth 1 even with checks everywhere then we
have different definition of everywhere so you should expalin your definition of
everywhere.

extending escape to checks everywhere is not enough to search checks everywhere
and you need also to generate all possible checks everywhere.

If after some checks by the black rook you stop generating rook checks then you
do not generate checks everywhere.

I do not believe that Diep or Hiarcs or Chessmaster extend checks everywhere by
my definition.

Uri



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