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Subject: Re: Amazing, Fruit 2 needs several mins to solve Fine 70

Author: Dieter Buerssner

Date: 06:08:55 03/20/05

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On March 20, 2005 at 03:33:05, Fabien Letouzey wrote:

Hi Fabien,

>Did you store separate drafts for the two bounds?

Yes. I had one draft/score for lower-bound and exact, and one draft/score pair
for upper bound. Only one move, for the lower-bound. Hmmm, perhaps this was bad.
Normally (with the hash entry with only one score) my engine also stores a move
for upper bound (the best move of a fail-soft search, which surprisingly often
is really a good/the best move, and in tests done long ago, this was clearly
better than not storing a move for fail low).

As I said, for some reason in general depth preferred seems more critical, than
always replace. I thought, the problem could be, that with depth preferred you
have deep entries, that you keep. But the situation changes, and those entries
have the wrong bound and are useless for cutoffs. So I hoped, with 2 bounds, I
could tune the HT a bit more on the direction of depth preferred (and it even
seemed to work a bit in some test positions), but in practice it seemed almost
100 Elo worse. It was a bit frustrating, because I could not find anything.
Perhaps I gave up too early.

Cheers,
Dieter



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