Author: Bas Hamstra
Date: 06:58:10 01/17/00
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On January 17, 2000 at 09:32:40, Robert Hyatt wrote: >On January 17, 2000 at 03:11:34, Jouni Uski wrote: > >>Yes stunnigly they are available at: >> >>http://www.research.ibm.com/deepblue/watch/html/c.html >> >>First thing I notice is, that search depth is not very convincing at all - >>mostly 11-12 ply (also in endgame part)! Have I read log wrong way? Most >>Chessbase engines got same ply in standard PC... >> >>Jouni > > >It is a "different" kind of ply. DB didn't use null-move of any kind. They >also used singular extensions which cause the typical chess ram to search >1-2 plies less deep in the typical case, although it will probe much deeper >in the traditional sense. One other unknown is whether their 10 plies includes >the 4 plies of hardware search. They don't count total nodes that I noticed >anywhere, so it isn't easy to decide. For me, 1M nodes per second gives a >depth of 13-14 in the middlegame. Going 200M should drive that to roughly >log3(200) which is about 5 plies deeper. So call that 18-19 plies. Removing >null-move would subtract 2, so 16-17 plies. Singular extensions 1-2 more plies, >so that would be (14-15) to (15-16) plies. I am not sure this is correct. Are you saying when Crafty searches 19 plies with nullmove R=2, it must search 17 plies without nullmove? As far as I know without nullmove and other pruning tricks your branching factor is 4,5 and with nullmove it is 2,5. I don't think you can simply subtract R at any depth. I'm not sure though. It's easy to test anyway... Regards, Bas Hamstra. >Somewhere on their web site they mentioned 14 plies as "normal". So their >iteration number might be slightly different from "ours". IE when I search >until depth is reduced to zero, I go to the quiescence search. They might >go to their hardware, which is not exactly a "quiescence search" since it looks >at all moves for 4 plies, but doesn't do any of the singular stuff and so forth. > >I'll try to ask next time I hear something from Hsu.
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