Author: Vincent Diepeveen
Date: 05:40:10 08/08/00
Go up one level in this thread
On August 07, 2000 at 20:06:28, Dave Gomboc wrote: >On August 07, 2000 at 05:58:44, Andrew Williams wrote: > >>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 > >Judea Pearl's work was the inspiration for mtd() methods, but I agree, it's not >conclusive. > >Dave Note that my program at a 32 bits processor is exactly 2 times faster as crafty with datastructure, and attacktables and mobility go hell of a lot slower with bitboards, unless you're happy with something rude. Note that DIEP engine is completely ANSI-C. Crafty is basically inline assembler in this respect. it even assumes in what registers things get loaded. Bob is very happy with having something rude, and he looks forward to 64 bits cpu's that have the instructions he needs for bitboards. So his goal is not the same as mine. I'm for now busy with 32 bits machines. If i can afford a 64 bits machine which huge part of the world also can afford, and if on that 64 bits machine bitboards are for certain purposes faster, then sure i'll have them within a week. Greetings, Vincent
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