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Subject: Re: Nullmove: when to avoid it?

Author: Severi Salminen

Date: 13:56:11 03/02/01

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>>Yep, that's true. As Bob said it is very rare to have beta=INF. Actually
>>Beta=INF can occur only in the very beginning of the search until we get our
>>first real score (score<=INF-Ply). Remember also that you don't have to know
>>anything else about the nullmove but whether its score is >=beta. So you can
>>search with (-beta,-beta+1)
>>
>An idea I had, is that since about half the time we expect a move to fail low,
>it doesn't make much sense to give the opponent an extra move and expect it to
>fail high.

Well, the point is: how do we know it _before_ trying the null move? Futility
(pre) condition is one good indicator: if(depth==1&&material+MARGIN<=alpha).

Severi



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