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Subject: Re: qSearch and stand pat question

Author: Anthony Cozzie

Date: 06:36:39 11/04/03

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On November 04, 2003 at 06:42:56, scott farrell wrote:

>Consider the position below, just moving into the qSearch my engine tries the 2
>checks, and RxP.
>
>The checks lead to a qsearch for white that looses the rook. The RxP leads to a
>qsearch for white of the promotion.
>
>Clearly it doesnt like any of these moves, so it just takes the stand-pat at the
>node it is at. As such it is horizoning the fatalities in the qsearch.
>
>Is this correct?
>
>How many people use stand-pat ala crafty? Who uses what else?
>
>even though my engine has the pawn promotion in the qSearch, the stand-pat stops
>it from playing it.
>
>A 1 depth search from this node, gives me 75 nodes, and the score drops by 5 for
>black.
>
>One solution I can see is to staticly evaluate the rook as lost, so it wont
>stand-pat at the node. My evaluate function doesnt really consider who's move it
>is, to see the rook is undefended and under attack, and sideToMove is going to
>allow its capture. I have some eval code for pinned pieces and enpris and the
>like, but low values - it would seem to me here I could statically say the Rook
>is lost.
>
>The only other solution I can think is to let the other side make its qsearch
>moves anyway, sort of like null-move, and given they all fail-high for white,
>dont allow the stand pat or something (sort of like dont allow stand-pat during
>checks).
>
>[D] 8/PP4pk/4R2p/4p3/8/8/1K6/r7 b - - 0 61

I pretty much agree with Tord here.  The problem is not Black's rook, it is the
advanced white pawns.  The rook is not lost - black can play Ra6 or Rh1 or
something and save it.  Two connected passed pawns on the 7th are at LEAST 1
rook imo.

anthony



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