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Subject: Re: Problem with draws by rep and hash table - solution?

Author: Bruce Moreland

Date: 12:08:21 10/08/99

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On October 08, 1999 at 12:52:23, Eugene Nalimov wrote:

>I think there is a simple solution: from the search() function return not only
>the score, but also a flag "path information was used". That flag should be set
>if
>
>(1) draw by repetition was detected,
>(2) 50 moves rule was used,
>(3) any of the searched children of the node returned that flag.
>
>Before storing to the hash table, check that flag, and if it's set, do not store
>the score, store only the best move.
>
>I am not sure the overhead of the solution is tolerable, and maybe it's better
>just to ignore the problem, but I think the proposed solution will cure the
>problem once and for all.

I haven't thought about this much, but I don't think that there is any way to
turn this flag off for an ancestor node once a descendant turns it on, unless
you are willing to search sub-trees that you wouldn't otherwise search.

So once you find a rep, don't you destroy everything above that node?  There are
a lot of reps.

But yes, this solves it.

I think the problem doesn't cause much damage as long as you can tolerate your
search returning random crap.

bruce



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