Author: Robert Hyatt
Date: 11:31:17 12/07/99
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On December 07, 1999 at 09:02:37, Vincent Diepeveen wrote: >On December 06, 1999 at 15:33:03, Robert Hyatt wrote: > >>On December 06, 1999 at 13:00:56, Georg v. Zimmermann wrote: >> >>>>A thousand fold increase would be >>>>what, an additional 6 ply search in the same time? >>> >>>Lets do some math. 40^x = 1000, 40log 1000 = x, x = 10log1000 / 10log40, x = >>>3/10log40 = 3 / 1.5 = 1.9 >>> >>>I think it gets you "1.9 ply" deeper if you do brute force. Now we need someone >>>to tell us how much that is if you add HT and other modern wunder drugs. >>>But I would be very very suprised if you'd reach +6ply. >> >> >>DB has an effective branching factor of roughly 6, about the same as Cray >>Blitz, which didn't use R=2/recursive null move. Log6(1000) is at most 4, >>so it would get about 4 plies deeper. Certainly nothing to sneeze at... > >see different post of me. DB may be happy with a b.f. from 10.33 > >>But then again, this math is really wrong, because for each cpu, DB used >>16 chess processors. Each chess processor could search about 2.4M nodes per >>second (they used almost 500 for DB2 the last match). With one million >>processors, they would then have 16M chess processors, and would be >>searching about 40,000,000,000,000 nodes per second. At about 1 billion >>(max) for DB2, this would be 40,000 times faster. and log6(40000) is 6, >>so they could hit about 6 plies deeper. Very dangerous box... > >the more processors the smaller the speedup. just attaching all processors >to the search might take a few minutes. > >Note that HSU writes that they got very close to 1 billion positions a >second but never hit the magic 1 billion positions a second number. > >Vincent Sure.... hitting 1B is not easy when you have _just enough_ chess processors to peak at 1B. But to hit 1B requires perfect speed-matching between the chess processors and the SP, which doesn't happen. I think he said that the chess processors were running at about 70% of max speed because of this. And he also claims 30% efficiency (in a linear way) in his parallel search. Which means that no matter how many processors he adds, he gets about 30% of each one. As far as branching factor, he uses normal alpha/beta, so I have no idea where you would get 10+.
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