Author: Stuart Cracraft
Date: 11:33:25 12/28/05
Go up one level in this thread
On December 25, 2005 at 08:35:36, Vincent Diepeveen wrote: >On December 25, 2005 at 08:25:12, Vincent Diepeveen wrote: > >>On December 23, 2005 at 18:22:29, Jonas Cohonas wrote: >> >>>As far as know deep blue was based on an actual chess playing program (please >>>correct me if am wrong) Dark Thought, does anyone recall the k/Ns for Dark >>>Thought on a regular PC at that time? >> >>>I am asking this because we could maybe make an estimate of how Dark Thouhgt >>>would perform k/Ns wise on PC's of today and get a better understanding of what >>>the real speedup was on Deep Blue. >> >>>Maybe i am confusing the program Deep Blue was build up around and maybe it is >>>not comparable (apples and oranges as Bob would put it), but if feaseble it >>>would make for an interesting comparison/experiement. >> >>>Regards >>>Jonas >> >>Hello Jonas, >> >>Dark Thought had an assembly port to alpha. The biggest improvements in >>darkthought and optimizations were done by Peter Gillgasch, someone who really >>understood chessprogramming and was state of the art chessprogrammer at the >>time. >> >>In world champs 1997 darkthought searched at a 767Mhz alpha 21164. This machine >>has 8KB L1 cache. Fastest PC at the time was a 300Mhz PII, which you could not >>buy yet in a shop. Worldchamps 1997 was in october in Paris. >> >>Darkthought had a maximum of 1 million nodes a second. >> >>However please realize how restricted its search was last plies. >> >>To quote Peter Gillgasch: "it's so stupid that everything gives a cutoff, >>which makes search very easy". Ferret was also there in 1997 at a 767Mhz alpha. >> >>It reached 14 ply in the game against me, which started as a complex middlegame >>in sicilian (diep black side). >> >>In 1999 programs were improved a lot. Darkthought was still the same. Ernst A >>Heinz had made a fight with Peter Gillgasch, though i do not know cirumstances >>at all. Whatever happened there is perhaps interesting for insiders to know, but >>what matters is this: Peter Gillgasch had left Darkthought, so no chance of it >>ever improving. >> >>Deep Blue was a far simpler program. It has been made by hand in the hardware >>logics. So it has not been made in verilog, but using the utmost lowlevel >>components that are there in hardware. So you must make a program then by cut'n >>pasting logical hardware blocks. This is the hardest way to program a machine. >> >>That Hsu got a chessprogram like that to work is really amazing. >> >>It didn't use nullmove and had a very limited evaluation function. Well you can >>see that from the games and its logfiles of course. Deep Blue initially was a >>simple piece square table program. Later on they took over a few Gnuchess 4.0 >>components, but of course in hardware programming is so hard, that you must >>expect gnuchess to have more knowledge than deep blue. >> >>Of course very important to realize is that in 1997 and before it was normal for >>programs to be true beancounters. Later on chessprogrammers discovered that a >>bit more agressive tuning of evaluation gives great play. The honour of that >>invention really goes to Chrilly Donninger. >> >>It is very easy to figure out the search speed of Gnuchess 4.0 at todays >>program, however gnuchess 4.0 is way more sophisticated than Deep Blue, yet it >>has a few obvious bugs in easy eval terms. Gnuchess for example has nullmove, >>deep blue doesn't have that. >> >>Just imagine how hard it would be to implement nullmove in hardware. >> >>Deep Blue didnt use killermoves in hardware. Imagine a 4 ply search in hardware >>which already is terrible inefficient, then also not using killermoves. >> >>A single search of 4 ply in hardware without any sophisticated move ordering, >>with a huge quiescencesearch and no nullmove and no killermoves, no history >>moves, no move ordering at all except captures first, you can try yourself too. >> >>It is terrible inefficient, but good for your nodes a second. You can easily >>search 4 million nodes a second like that at todays processors. There is no >>bottleneck. No hashtable, nothing to stop search speed. >> >>But you will search just like Deep Blue around 10 ply first move out of book. >> >>Vincent > >Note that if you search like deep blue you will get that 10 ply only if you have >480 processors @ 2 million nodes a second with a terrible speedup. > >Note that Deep Blue severely restricted extensions and also forward pruned in >hardware in order to get that 10-11 ply. > >There is a pdf document describing their extension system. Their dual threat >mechanism is pretty clever taking todays search depths into account. > >Vincent Not pdf since unavailable but html at least: http://66.102.7.104/search?q=cache:2HidIj2QvY4J:deron.csie.ncue.edu.tw/AI/paper/ppt/49.pdf+anantharaman+dual+threat&hl=en&client=firefox-a
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