Author: Robert Hyatt
Date: 08:26:02 01/22/98
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On January 22, 1998 at 09:01:59, Ernst A. Heinz wrote: >On January 22, 1998 at 08:42:06, Robert Hyatt wrote: > >>Yep... Forgot. For me, I couldn't do the above... because I don't use >>fail-soft and most scores (excepting mate and draw) are always inside >>the alpha/beta window. But shifting the null-move window down does >>exactly the same thing, ie searching alpha-piece, beta-piece produces >>the same information. > >Yes, but it is much more expensive because you must do a second null >move search whose trans/ref efficiency is probably bad because of the >shifted search bounds. Furthermore, the condition of the static >evaluation failing high is important. actually it is not that expensive, because it is hardly ever done. Only when backing up a score that is not alpha (meaning this is either going to fail high unexpectedly or else this is a true PV search.) The null move wasn't the real killer for me at all, because I used to have code to measure how much extra searching I did. The killer was extending moves that really didn't do anything good for the search, except burn CPU time... > >>I thought my idea of first noting that this was a PV move, and then >>trying the null-move threat extension only after that was from the >>paper. > >As you can only do a non-zero window null move search somewhere down >the PV, this is certainly implied by the paper. > >=Ernst=
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