Computer Chess Club Archives




Subject: Re: When to RecordHash()?

Author: Robert Hyatt

Date: 20:56:56 12/25/01

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On December 25, 2001 at 20:21:49, Sune Fischer wrote:

>I'm sitting here with an implementation problem, I can think of a few ways to
>solve it, but perhaps there is an even better one.
>The problem is I can't always get the best move in a position when searching, I
>need a beta cutoff or an improvement in the alpha value. So it isn't save for me
>to assume there is killer in all recorded hash entries, and if I only
>recordhash() when I _can_ put a killer in, then I miss out on some scores.
>So I was wondering what solution you guys have found?

If I understand your question, there are three kinds of positions where you
can store a hash entry.  PV entry where the score is _EXACT_.  You should
have a best move to store hre.

LOWER entry which is AKA a fail-high position.  A move caused this fail high
and it should be stored in the hash as best.

UPPER entry which is AKA a fail-low position.  There is _no_ best move in this
position.  I simply store a 0 for such cases...

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