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Subject: Re: negative extensions

Author: Edward Screven

Date: 10:37:31 01/25/01

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On January 25, 2001 at 13:12:55, Miguel A. Ballicora wrote:

>>applying david's suggestion to a null move implementation would
>>mean reducing the search depth after a null move failed high
>>instead of simply returning immediately with a fail high.
>
>That is what I do with in my program Gaviota (not a good example since
>it is still a beginning project). Instead of returning beta I do
>
>depth = depth - R;
>
>I does not reduce the tree as much as classic null-move but still reduces
>enough. The advantage is that it is not fooled as easily by zugswang-type
>positions. A couple of plies more and it sees it. Some of the positions
>that have been posted here that are tough for excellent null-move programs
>Gaviota was ok.
>Probably not as good as null-move since zugswangs are rare but I just like it.

what do you do when the null-move fails high, then the reduced
depth search doesn't?  do you then re-search at the original
non-reduced depth?

i vaguely remember trying something like this as a kind of null
move test verification step.  i took it out, so i must not have
liked it.  i'm pretty sure i heard about the idea from someone
else.

  - edward




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