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

Author: Inmann Werner

Date: 11:22:49 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.
>
>Eugene
>

Maybe, i was not exact enough..
That is, what i do now, because I have no better idea.

But it does not really solve the problem.
You store the rep move as a best move, but is it really? You only know, it is
good cause of the rep, but it can be bad also.
Second, if you again come to this position, especially if it is at the beginning
of the search, you do not have the hash and have to go through the full search
again. Escpecially in endgame with some material, this very often happens, and
slows down a lot.
So often, you get a better result in ignoring the problem and doing full
hashing. :(
I think, it is not solveable, but you should know the problem, so not being
astonished, if some strange things occur with it....


Werner





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