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Subject: Re: Interesting search extension data

Author: Will Singleton

Date: 18:35:10 01/25/01

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On January 25, 2001 at 09:41:41, Robert Hyatt wrote:

>On January 25, 2001 at 00:16:04, Andrew Dados wrote:
>
>>Thanks Bob for very interesting report.
>>A couple of loose thoughts...
>>
>>Recapture extension is intuitively no good for tactical suite for a simple
>>reason: all tactical lines give up temporarily material. And lines with
>>exchanging down pieces are not 'beautiful' for humans - which was probably one
>>of conditions for selecting a 'tactical' position into set like WAC.
>>
>>It is hard to say if your program plays weaker or stronger in practical games
>>because of it. And, btw, one of Craftys strengths is exchanging down to won
>>endgame. Maybe some sort of nunn-type match between 2 versions can give more
>>data about it?
>>
>>And if you come down to think about the trend - It would be interesting to run
>>your test with recapture extension going below zero....:)
>>
>>-Andrew-
>
>Ken Thompson got me started on this in the early 80's.  The idea is that
>if you are in some kind of trouble (say losing a pawn) then one way to help
>"hide" this is the good old BxN PxB sequence.  BxN forced the opponent to
>recapture the bishop, and that eats two plies of your total search, maybe
>hiding the pawn loss.  Extending a ply partially offsets this...
>
>But I have never tested it very thoroughly.  I am going to turn it off on
>one version and play an extended match, 2cpus to 2cpus..  I'll report on the
>result later..

I predict the capture extension version will win easily, especially in medium
blitz games (5 0).  I have done that test (but not the wac test), and my program
definitely plays better with a limited capture extension.



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