Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Hashtables and iterative deepening (question)

Author: Andreas Herrmann

Date: 11:02:29 05/13/02

Go up one level in this thread


On May 13, 2002 at 08:48:36, Vladimir Medvedev wrote:

>I'm going to implement hashtables in GreKo (they will be in ver. 0.42, now I'm
>testing their work).
>
>The question is, how to manage hashtables while iterative deepening is used?
>Now I clear hashtable on each iteration, because holding them unchanged since
>last iteration causes search instability. But I feel that I lose some useful
>information this way...
>
>Please, could anybody give me some information, weblinks or advice on this
>technique?
>In addition to http://www.seanet.com/~brucemo/topics/hashing.htm, which is the
>main knowledge source for me now?

If you don't find your error in your hash code at the moment then try the
following:
Store inside your hash entry a value like "hash age". You can calulate such an
hash age for excample "MoveNo modula 255" (so you need only one byte) or a
similar value.
Instead of deleting/clearing your hash entry you can simply compare this
HashAge.
I use something like this, to be sure i'm using not too old entrys from the
hash. AFAIK Robert Hyatt's Crafty has something similar in his hash entry.

Andreas

http://wbholmes.de







This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.