Author: Robert Hyatt
Date: 14:44:44 01/22/00
Go up one level in this thread
On January 22, 2000 at 15:18:53, stuart taylor wrote: >On January 22, 2000 at 10:30:25, Robert Hyatt wrote: > >>On January 22, 2000 at 05:40:11, blass uri wrote: >> >>>On January 21, 2000 at 22:54:36, Robert Hyatt wrote: >>> >>>>On January 21, 2000 at 17:22:08, Amir Ban wrote: >>>> >>>>>On January 21, 2000 at 15:08:16, Robert Hyatt wrote: >>>>> >>>>>>On January 21, 2000 at 13:56:40, Tom Kerrigan wrote: >>>>>> >>>>>>>On January 21, 2000 at 11:44:22, Robert Hyatt wrote: >>>>>>> >>>>>>>>It would run so much slower it would get killed tactically. Remember that their >>>>>>>>king safety included not just pawns around the king, but which pieces are >>>>>>>>attacking what squares, from long range as well as close range. Which pieces >>>>>>>>are attacking squares close to the king, etc. That takes a good bit of >>>>>>>>computing to discover. >>>>>>> >>>>>>>I realize that it takes a good bit of computing to discover. But I doubt it >>>>>>>takes so much that it's prohibitive. There are very successful micro programs >>>>>>>with extremely expensive evaluation functions, e.g., MChess and the King, and to >>>>>>>a lesser extent, HIARCS and Zarkov. These programs all reportedly have terms >>>>>>>similar to the ones you describe. I seriously doubt that the DB evaluation >>>>>>>function is an order of magnitude more complex than, say, MChess's... >>>>>>> >>>>>>>-Tom >>>>>> >>>>> >>>>>Add Junior to the above list. >>>>> >>>>> >>>>>> >>>>>>But they don't take the time to find out which pieces are attacking squares >>>>>>around the king "through" another piece. IE a bishop at b2 attacking g7, but >>>>>>only if the Nc3 moves. Or only if the pawn on d4 or e5 moves. That gets very >>>>>>expensive computationally. DB gets it for nothing. I think it would slow me >>>>>>down by a factor of 100 or more, depending on how far I wanted to take it... >>>>>> >>>>>>That might make me more aware of king attacks, but it would hide many plies >>>>>>worth of tactics since a factor of 100 is over 4 plies. Only a wild guess >>>>>>of course on the factor of 100, but since the eval is done at every node in >>>>>>the q-search, this is probably within an order of magnitude or two of the >>>>>>real answer. >>>>>> >>>>>>I can guarantee you it is more complex than the above evaluations. And I don't >>>>>>even know all the things they evaluate. One new idea mentioned in Hsu's book >>>>>>was the concept of "a file that can potentially become open" so that you put >>>>>>rooks on that file, even though you can't see exactly how you are going to open >>>>>>it within the 15 plies + extensions they were searching. "Potentially open" >>>>>>takes a lot of analysis on the static pawn structure. I do some of this >>>>>>pawn structure analysis myself, and even with pawn hashing it slowed me down >>>>>>significantly when I added it a year+ ago to better handle/detect blocked >>>>>>positions. >>>>>> >>>>>>Remember that they claimed about 8,000 static evaluation weights in their >>>>>>code, this reported by someone that went to a DB talk by Murray Campbell. >>>>>>8000 sounds like a big number... >>>>> >>>>>It's big, but what does it really mean ? Some of it must have been piece-square >>>>>tables for some features that were downloaded from the hosts, and that's >>>>>hundreds of entries per feature. >>>>> >>>>>Besides, where is all this sophistication showing up in the DB & DBjr games ? >>>>>Forget the numbers, whatever they mean. Show us the positions & moves. >>>>> >>>>>Amir >>>> >>>> >>>>It would seem that the _results_ would speak for themselves. Who else has >>>>produced results like theirs? >>> >>>The question if their good results was because of deeper search or because of a >>>better evaluation function. >>> >>>You cannot get answer for this only by the results. >>> >>>Uri >> >> >>No, but if you take the 40 games Hsu/Campbell played against micros in their >>lab, with a very slow single-processor version of DB, you might conclude that >>speed wasn't all they had. IE 38-2 was the reported result that several >>reported here after attending talks by the two. That is evidence that they >>are doing something quite good... > > > Didn't I see in "Selective Search" Some time after the last DB vs Kasparov >match, some games played by DB against some comercial program where DB was >without its main speed hardware, and DB in that case was far inferior to >top comercial programs? >S.T. No. Because deep blue can't play "without its main speed hardware". It is based totally on hardware.
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