Author: Robert Hyatt
Date: 05:46:18 08/02/01
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On August 02, 2001 at 04:27:01, Bruce Moreland wrote: >On August 02, 2001 at 03:54:39, Dann Corbit wrote: > >>On August 02, 2001 at 03:44:01, Janosch Zwerensky wrote: >> >>>Hi all, >>> >>>I read some time ago that Deep Blue wasn't using heuristic game tree pruning >>>methods (like, for example, the null-move technique). >>>Since null-move was known when DB was around, can anyone here tell why the DB >>>team decided not to use it (or wasn't able to do so)? >> >>Safety. >>But don't imagine brute force mini-max. Not like that at all. As a matter of a >>fact, beyond 30 seconds, wonderful things might happen. > >When I started doing computer chess there were people searching (gasp!) nine >plies, and some of these people were talking about how the tree is way different >when you search that deep. There was talk of tactical sufficiency and lots of >other craziness. > >Now that we can do nine-ply searches in blitz games, a lot of that talk drops by >the wayside. > >I've always wondered about DT/DB and null move. It may be that they had >everyone so incredibly supersetted that they didn't need to mess with stuff like >this, but I'd think it was pretty incredible if they were still not using null >move. > >Null move is great, and as far as I can tell it works at any tree depth. > >This is one of the reasons I don't just keel over and die when Bob argues that >they are so bloody fast, and therefore they must be godlike. Yes, they are >fast, but they don't use the same kind of search. Maybe 98% of that tree is >crap, because against a human or a micro program running on a 286, it makes >sense to not make pruning mistakes rather than search an extra five plies (all >numbers approximate and probably way off). I don't know. There are ways to >find out, but they involve being able to test the thing. > >bruce Just remember, not _everybody_ today is using null-move. Yet their programs are still incredibly strong.
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