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Subject: Re: passed pawn extension

Author: Robert Hyatt

Date: 06:53:21 01/29/02

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On January 28, 2002 at 23:20:45, James Swafford wrote:

>
>Does anybody do this?  I just implemented a passed pawn extension
>that extends the depth by 1 if the move was a pawn move to the
>sixth or seventh rank, and that pawn is not blocked by a pawn of
>the opposite color.
>
>The results are pretty disappointing.  It really blew up my search.
>I decided to modify the implementation by saying only looking for
>pawn pushes to the seventh rank, and it still can blow up pretty
>bad.
>
>Obviously most over the board positions would not trigger this
>extension, but there are some that would blow up the search like
>mad.
>
>One thought I had is to use a fractional extension scheme.  That
>may help, but I'd like to know if anybody else does this extension,
>and what mechanisms they have in place to keep the search bloat
>under control.
>
>It's interesting to note that Bruce lists five different extensions
>on his (excellent) web page; he hasn't actually written about any of
>them yet, but passed pawn isn't even listed.  Hmm...
>
>Any ideas or comments?
>
>--
>James


I extend 3/4 ply when a passer reaches the 7th.  But that only happens on the
ply where it is pushed to the 7th...



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