Author: Jeremiah Penery
Date: 17:37:35 12/21/99
Go up one level in this thread
On December 21, 1999 at 15:34:26, Vincent Diepeveen wrote: >How efficient was the search of Deep Blue? >Let's compare Diep searching FULLWIDTH (so no pruning at all!) >with Deep Blue fullwidth. I hope you're including turning off Null-Move also? >Hsu writes in a paper that Deep Blue searched near 1 billion nodes a second >but never came over that number. 1 billion nodes was the maximum possible speed from the processors. When parallel loss is factored in, along with other speed losses in this case, DB was really only getting around 200M NPS in the games. >At a machine never getting 1 billion but getting over it, let's say >800 million nodes a second, which just starts with 12 ply after more >than 3 minutes, we talk about next estimation: > 3 minutes * 800 M/s = 180 * 800,000,000 = 144 billion nodes With the real speed DB was getting, it's more like 45 billion nodes in 3 minutes. (@250M NPS, which is still probably higher than it was truly getting.) > Diep needs 49957263 nodes. Let's see how many more nodes Deep Blue > needed: > 144 B / 50M = 144000 / 50 = 2880 times more nodes needed by Deep Blue. Should read: 45B/50M=900 >In the same article Hsu writes that in the hardware deep blue isn't doing >forced moves extensions, so that means that this search of DIEP picks up >a lot of more tactics there, where i'm doing ESPECIALLY near my leafs >extensions. They were doing the singular extensions in software, but many of the other extensions in hardware. They didn't just use the "extend 1 ply" stuff, either. In many cases, DB was extending multiple plies along singular lines. In the average position, it was around 11-12 ply full-width, with well over 40 ply extended. That's quite a lot of extensions. >So branching factor is about 3 of DIEP in this position (obviously >because most lines lead to an endgame). Again, I hope null-move is turned off? >Let's now see how deep DIEP would search with bf=3 with 144 billion nodes. > extra depth = log( 144000/520 ) / log ( 3 ) = 5.12 ply > >So 13 ply + 5 ply = 18 ply. >Diep would finish 18 ply here fullwidth, starting with 19. Assuming a relatively constant branching factor of 3... >Compare that with Deep Blue getting 11 ply here fullwidth, this considering >that in the leafs DIEP sees a lot more than Deep Blue. How do you know Diep sees "a lot more" than DB does in the leaves? >Now you might cry about DIEP not having singular extensions? >Well that's no problem. In the 11 ply search deep blue got, it could >only extend 11 - 5 = 6 ply (not extending in root i suppose and for sure >not extending last 4 ply in hardware). Secondly i remember some work >done on extensions that prevents it from keeping extending the same move. >So Deep Blue would see (not counting checks of course as those get >extended anyway in both programs): 11 + 6 = 17 ply at maximum. This is grossly wrong. See above my comment on DB's extensions. >Now DIEP searches without singular extensions with the same number of nodes >another ply deeper, not to mention that interesting lines don't have too >much singular extensions! The interesting lines should have the most singular extensions, or else they're not the most interesting...?
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