Author: Uri Blass
Date: 09:05:12 08/21/02
Go up one level in this thread
On August 21, 2002 at 11:21:18, Robert Hyatt wrote: >On August 21, 2002 at 10:35:13, Vincent Diepeveen wrote: > >>On August 21, 2002 at 10:26:57, Terry McCracken wrote: >> >>hello, >> >>Another thing. >> >>In 1998/1999 Hyatt claimed that deep blue searched 11 to 12 ply, >>but that their *extensions* were better than everyone else. >> >>They used singular extensions. >> >>In 2000/2001, i also was using singular extensions, as well as >>several other programs. > > >And as I said, your implementation is pitiful compared to _real_ SE >as implemented in Deep Thought/Deep Blue, Cray Blitz and HiTech. You >totally fail to handle the FH-singular case which is complex and expensive. > >And you _also_ fail to remember that you have said _many_ times "singular >extensions suck and what I do is much better". Only later you discover that >your _implementation_ sucked and than when you finally got it right, then it >did work pretty well. > >Which is typical for you, of course... > > >> Then suddenly when we searched above 11 to 12 ply >>depths, it was said that the 12(6) of the machine which means 12 ply >>nominal search depth, was excluding 6 ply hardware search depth. > >Directly from the team, remember. I posted the email _right here_ to >make it public... > > >> >>Which is bloody idiocy in itself, because the thing had no hashtable. >> >>The big theoretician Knuth has written a lemma for game tree search. >> >>The minimum tree to search at 18 ply search depth using alfabeta >>(without nullmove which wasn't used by deep blue): >> >>2 * (squareroot(number of legal moves) ^ depth) >> >>or: >> >>2 * sqrt(40)^18 = 524288000000000 nodes needed to search it *minimum*. >> >>As you can imagine, getting 11 to 12 ply fullwidth search was already a >>very good achievement in 1997. > > >Again, your theoretical explanation is wrong. How do you explain that Knuth's >"lemma" (as you wrongly call it) predicts a branching factor of > 6, when we can >_prove_ that DB's branching factor was under 4? I do not think to continue to argue here but only one point: We cannot prove that the branching factor was less than 4. The output is not a proof because people can choose not to believe that 12(6) mean 18. If someone can make a free program with branching factor of less than 4 inspite of no pruning(except futility pruning) then it may be interesting to see. Uri
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