Author: Jeremiah Penery
Date: 14:44:11 10/16/02
Go up one level in this thread
On October 16, 2002 at 11:05:50, Uri Blass wrote: >On October 16, 2002 at 09:40:21, Jeremiah Penery wrote: > >>On October 16, 2002 at 07:31:01, Vincent Diepeveen wrote: >> >>>On October 15, 2002 at 13:31:07, James Swafford wrote: >>> >>>There is 2 things >>> >>> a) theoretic branching factor without nullmove >>> >>>that's true for the last so many plies of deep blue and >>>the theoretic truth. >>> >>> b) branching factor with hashtable. >>> >>>You will see that deep blue is somewhere, like all software programs >>>in the middle of this. >>> >>>126 mln nodes a second. And it got like 12 ply with a bit more >>>than 3 minutes. >>> >>>that's like total branching factor = 12th root from >>>126 mln * 180 seconds = 6.0 >> >>If you mean (180*126m)^(1/12), that equals 7.294. >> >>>So the real overall b.f. which was achieved was 6.0 >>> >>>that's lower than the theoretic branching factor of sqrt(40^18) >> >>If a decent program didn't have a lower number than the 'theoretic branching >>factor...' I'd be very surprised. > >I believe that it is possible to get >a good program with branching factor of 6 >and a lot of extensions. I didn't say it was impossible, I said I'd be surprised by it. However, now that I think about it, Chessmaster might have that kind of branching factor. >I see no contradiction >plies do not have to be eqvivalent. Ah! This is the important statement. Vincent seems not to understand it. >>BUT, if you insist on this number, and you think they only got 12 plies, they >>need to search 4096000000 nodes for 12 plies. They can accomplish that in 32.5 >>seconds with 126M n/s. 12.2 plies takes 47 seconds. In 180 seconds, they can >>do 12.93 plies, in fact. sqrt(40) is a branching factor of 6.32. With a >>branching factor of 6, they can reach 13.3 plies in 180 seconds based upon your >>formula. > >No > >You forget that there is also a constant. >If the number of nodes to get depth n is >a*6.32^n I see no problem. Problem with what? The real problem here is trying to calculate their branching factor with this formula. The formula assumes the search tree is perfectly uniform, and theirs was highly NON-uniform. Therefore this particular calculation is meaningless. I only used it because Vincent seemed insistent upon using it.
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