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Subject: Re: questions about singular extensions

Author: Robert Hyatt

Date: 02:14:36 08/10/98

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On August 10, 1998 at 02:07:54, Mark Young wrote:

>On August 09, 1998 at 23:09:20, blass uri wrote:
>
>>I know DB and Cray blitz use singular extensions (when one move is clearly
>>better than the others they analyze it more) and I have some questions
>>1) how much time do the programs analyze a move to decide it is singular.
>>Is it a function of the total time you give the program?
>>
>>2)what is exactly a singular move
>>(what is the minimal difference in evaluation between the best move and the
>>second best move to decide that a move is singular).
>>
>>3)In what lines do the programs use singular extensions?
>>
>>4)are there other programs who use singular extensions?
>>
>I had a test position that would test if a program used singular extensions. I
>lost the test position but remember that CM5000 could solve the position in less
>then 1 sec. meaning CM5000 used singular extensions. Other programs I tested
>could not solve the position at all. So they did not use singular extensions. If
>someone has this test position please post it.
>>Uri



Actually a test position can't identify this.  It might "suggest" that a program
does or doesn't use SE, but it can't prove it.  The singular margin can be
different, on different engines, which will affect what gets extended and what
doesn't...  some may only extend when material is being lost or won, while
others may extend on large positional score swings, etc.  I don't think *any*
micro can do *full* singular extensions because it is quite expensive, which is
why a couple have tried just PV-singular extensions, or "deferred singular
extensions", to keep the cost contained...



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