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Subject: Re: Hashtables and iterative deepening (question)

Author: Daniel Clausen

Date: 06:38:08 05/13/02

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On May 13, 2002 at 09:25:11, Georg v. Zimmermann wrote:

>Hi,
>
>hash tables are essential and should get you around 3x speed improvement on
>average.
>
>The whole idea of iterative deepening is (other than easier time management)
>to fill the hash tables, so clearing them between iterations is a bit silly
>:-).
>

[snip]

... among other things, like filling killer moves, history heuristics, getting a
PV. (fighting with the screensaver about CPU cycles ;)

Instead of clearing the whole HT, one could also just clear the scores but keep
the bestmoves. (which would need an additional value to hashfEXACT, hashfALPHA,
hashfBETA) Depending on what else an engine uses for move ordering, the
performance hit is maybe not too big this way.

But I'd also assume some major bug, when the search instabilities are that
noticable.

Sargon



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