Author: Andrew Williams
Date: 02:58:44 08/07/00
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On August 06, 2000 at 20:10:49, Vincent Diepeveen wrote: >On August 06, 2000 at 19:17:18, Tom Kerrigan wrote: > >>On August 06, 2000 at 16:37:24, Vincent Diepeveen wrote: >> >>>On August 06, 2000 at 12:45:11, Dan Andersson wrote: >>> >>>>Vincent has had this idea of MTD and never managed/bothered to defend it. I >>>>believe it to be an unsupported opinion. >>> >>>No commercial program uses MTD. End of proof man. >> >>I thought the MP version of Fritz does. >> >>-Tom > >I never saw any MP version of Fritz in the shops so far, >perhaps someone is gonna state soon that DB used MTD too. Oddly enough, this seems to be what Hsu says in his IEEE Micro article. Unfortunately, he doesn't say quite enough to be clear: "The search control does not really implement the regular alpha-beta search algorithm [Ref: Knuth & Moore 1975]. Rather, it implements a minimum-window alpha-beta search algorithm [Ref: Pearl 1984]" This is a bit ambiguous, because of course PVS could be called a "minimum window algorithm". But the rest of the paragraph (which is too long to type here) does seem to suggest that DB was using something more like MTD than PVS. I don't know if Bob knows for sure (maybe it's in Hsu's book?). Either way, I'd recommend looking at the article, "IBM's Deep Blue Chess Grandmaster Chips", Feng-hsiung Hsu, IEEE Micro March-April 1999. The relevant section is "Search Control" on page 80. Having said all that, I think your argument about commercial programs and MTD is flawed (whether DB used MTD or not). The problem is that MTD is a relatively new technique, like bitboards. AFAIK, no commercial program uses bitboards either. I know you don't like that technique, Vincent, but no sane person would say that the fact that they're not widely used in commercial programs "proves" that they're no good as an approach to creating chess programs. Andrew
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