Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: draw by repetition and hash tables

Author: Roberto Waldteufel

Date: 00:22:44 07/24/98

Go up one level in this thread



On July 24, 1998 at 00:38:01, Inmann Werner wrote:

>Hello all!
>
>can anybody help???
>
>I have some problem to implement draw by repetition in my program.
>If a position is reached the third time, its a draw by repetition. Ok.
>But the position has an evaluation. But because of the draw I return zero
>(draw). Now all positions before in alpha beta get a Score of zero. OK.
>But this values also may come into the hashtables, and thats really bad and
>not correct!
>Does anybody have the same problem, and maybe solved it?
>
>Werner

Hi Werner,

I am aware of the problem, but to the best of my knowlege there is no solution,
and most of us simply ignore it. This is an inaccuracy that you have to
tollerate as long as you hash *positions only*, with no reference to the precise
history of that position. A similar problem can occur with draws by the 50-move
rule, although this is less common. The speed you get from hash tables has a
price, but I think the price is worth paying!

Best wishes,
Roberto



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.