Author: Robert Hyatt
Date: 18:24:10 06/28/98
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On June 28, 1998 at 20:32:58, jonathan Baxter wrote: >So all this recent discussion about DB says it doesn't null move, and I saw >another post which said in some positions it was getting no more than 11-ply. >Since PC based programs now reach that easily (without heavy forward pruning >apart from Null move), but PC programs are not close to challenging Kasparov, >can't we only conclude one of two things: > >1) DB has a much better evaluation function than the PC programs. > >and/or > >2) Null moving makes *lots* of mistakes. without a doubt. It lets you find some things, but it screws up badly on others. That's the risk of "forward pruning" of any kind... > > >"1" seems unlikely in light of a quote I heard from one member of the DB team to >the effect that DB's eval was only "nearly as good" as the best commercial >programs. I believe this was an *old* quote. They have since said, on several different occasions, that they believe they are far better (evaluation- wise) now. This was true with the first deep thought/deep blue chip I think, but the new chip used in the last match had a truly significant increase in chess knowledge. > >So that leaves 2. This is news to me. Anyone have any comments? null-move is speculative. Cray Blitz is tactically stronger than any program I know of today excepting Deep Blue, based on things like the Win At Chess results I have posted here before. It uses null-move, R=1, non-recursive (only one null move in any single path). If you'd have had the opportunity to sit around the table with Hsu and company at any of the recent ACM events, you'd know his opinion of null- move searching. However, I should add, two years ago he thought my pruning in the q-search in Cray Blitz and Crafty was wrong, but then in DB-II he added such an idea. So you never know, although I can't see him doing null-move... That is directly opposed to the extensions they try to do. > >Jonathan Baxter
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