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Subject: Re: Can nullmoves behave like this?

Author: Vincent Diepeveen

Date: 12:28:25 01/08/01

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On January 08, 2001 at 14:17:47, Severi Salminen wrote:

>>i see you have 'futile moves' also. If you throw futility pruning out,
>>then nullmove should work brilliant positionally spoken.
>
>I tried, but the behaviour was the same. But then I removed my very stupid
>3-fold repetition algorithm (it is only adding different bitboards of a position
>to get a "key") and I got results with no fail highs or lows. I must find
>another way to find repetitions...

aha perhaps there is the bug then!

do you store repetitions in hashtable?

simplest solution is to never give a cutoff from hash if
it is score 0.00, that's what i do and it always worked.

>>Otherwise you reduce depth and let opponent to move then you prune
>>without trying the reduced depth even!
>>Usually that's tactically not missing too much if you implement a few
>>exceptions like allowing all captures, but it prunes positionally a lot!
>
>What do you mean by allowing all captures? You mean excluding captures from
>futility pruning - sounds odd?
>
>>Nullmove definitely should give also in endgame about same PV and same
>>score. Nullmove never can cause big problems, it can at most show
>>existing problems.
>
>Yes, advantages are _much_ greater than disadvantages, as you probably already
>have noticed :)
>
>Severi



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