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Subject: Re: questions about singular extensions

Author: blass uri

Date: 23:32:32 08/09/98

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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.
There are positions when progrmas have to calculate a move for some seconds or
some minutes to discover that the move is singular.

A good example for this is the 7th game Rebel-Anand after the line 33...Qe6
34.Bc6 Rc3 35.bxc3 Qc4 36.Bb2 Qxf1+ 37.Qc1
all the programs I know after many hours do the mistakes:
37...Qxc1+?(Rxb2 or Bxc3 is winning) 38.Bxc1 Rb1+?(Bxc3+ is a better move)
39.Kxa2 Rxc1 40.cxd4 Rxc6 41.d7 Ra6+ 42.Kb3 Rb6+ 43.Kc4 Rb8
(all the moves in this line are singular because the difference between the best
and the second best move after some minutes is more than a pawn)
and white is winning after 44.Kc5

The question is if CM5000 use singular extensions of these moves in
correspondence chess or use singular extensions only in cases it discovers in a
very short time that a move is singular.

Uri

>>Uri



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