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Subject: Re: Extended futility prunning not working

Author: Tord Romstad

Date: 12:07:46 08/04/04

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On August 04, 2004 at 14:53:03, Pallav Nawani wrote:

>Where pruning really shines is in endgame. I get 2-5 extra plies because of the
>(heavy?) pruning I do, some times even more.
>
>Pruning hurts tactical strength a bit, especially for a simple program like
>mine.

Funny.  This is almost exactly the opposite of my experience.

In the endgame, I haven't been able to find any kind of pruning which works
(except plain recursive null-move pruning with a small reduction factor).  All
the many pruning techniques I use in the middle game are ineffective in the
endgame.  I might get a few plies extra if I switch on various kinds of
pruning, but it introduces too many mistakes.  Heavy pruning in the endgame
hurts in test suites as well as in games.

I haven't found tactics to be a problem, though.  Heavy pruning greatly
improves the tactical strength of my engine.

Do you use the trick of avoiding most kinds of pruning when there has
been an extension at one of the last few plies in the current line?

Tord



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