Author: Vincent Diepeveen
Date: 11:25:32 08/21/02
Go up one level in this thread
On August 21, 2002 at 12:05:12, Uri Blass wrote: >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 Look their thing could do a billion nodes a second in theory. I know very well why it is for only 1 or 2 ply a branching factor of 4. I see it in DIEP too. After a few ply slowly more and more processors you can keep busy. If they only get an average of 126MLN nodse a second of a machine which in theory is capable of doing way more, then obviously somewhere they start with 1 processor and somewhere they manage to get them all at the same time busy. That explains why the branching factor is about 5 for just ONE Ply. Note that a fail high or low is already so much longer at 11 ply that calling it branching factor 4 or 5 is already way too little. Best regards, Vincent
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.