Author: Vincent Diepeveen
Date: 05:25:12 12/25/05
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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
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