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Subject: Re: Limited singular extensions. Anybody tried?

Author: Robert Hyatt

Date: 20:21:07 05/18/01

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On May 18, 2001 at 15:54:51, Dan Andersson wrote:

>I believe we are arguing somewhat the same thing here. If you have a dynamic
>measure (not based on forward search, but search history) with a predictive
>power of 90% (whatever) accuracy, would you not use it to decide when to enable
>a costly extension (that might fail).
>
>Regards Dan Andersson


No...  because the idea of singular extensions is to extend those moves where
there is only one good choice and everything else is significantly worse.  I
don't see how some history-based "trigger" would work very well here.  IE you
have to test a move for singularity in order to know whether or not it is
singular.  I'm not quite sure what I might try to use to determine that the
test is irrelevant, other than the few obvious ideas already known... ie no
point in doing a SE test if you are in check and you only have one legal move
to get out.  No point in doing a SE if you are recapturing a piece to restore
the material balance.  No point in doing a SE if the singular move is a piece
attacked by the opponent at the previous ply (otherwise the opponent could blow
the search up any time it is advantagous)...

IE I can think of history ideas on when to not do it...  but that leaves a _lot_
of open ground where they will be tried...  trying to restrict it more strongly
by trying to predict which moves _will_ be singular seems hard...

IE I read the two choices as (a) do like DB and test most all moves for
singularity;  (b) do something different and test a very few moves for
singularity.  (b) seems harder and more dangerous...



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