Author: Robert Hyatt
Date: 20:07:36 12/07/99
Go up one level in this thread
On December 07, 1999 at 20:38:22, Vincent Diepeveen wrote: >On December 07, 1999 at 16:07:36, Robert Hyatt wrote: > >>On December 07, 1999 at 15:25:11, Vincent Diepeveen wrote: >> >>>On December 07, 1999 at 14:31:17, Robert Hyatt wrote: >>> >>>>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+. >>> >>>See a post some higher. >>> >>>axb5 was a fail low. way over 3 minutes. >>> >>>800M * 180 seconds = 144 * 10^9 nodes. >>>11th root out of that is 10.33 >>> >>>simple nah? >>> >>>but the reason why is obvious: >>> - normal alpha beta without good move ordering is a crime >>> - no hashtables >>> - in the normal search DB did a lot of extensions >>> blowing up the search. extensions especially blow up the >>> search if you don't nullmove. >>> - i don't believe his 30% claim unless he was minimaxing. >>> >>>Vincent >> >> >>1. your math doesn't work.. because you have _no_ idea how many nodes it takes >>him to search a 10 ply tree. Effective branching factor = 11 ply time / 10 ply >>time. Anything else is a pure guess. I see nothing that they do that would >>drive the EBF beyond sqrt(38) which is roughly what alpha/beta is supposed to >>be. > >All measurements i do i get average number of legal moves = 40 at >depths above 10 ply. > >Now there are 2 options > - no extensions > - a lot of extensions > >Secondly sorting moves the last 4 ply is near to impossible, no >hashtable hits, so we can't compare it with our own good searches. > >No matter what you do, you're always getting very close to b.f. = 10 >At like 8 to 11 ply you can be still lucky, but then the >extensions of deep blue will blow it up, except if it does a lot of >less extensions than you claim it does. I just _love_ that kind of nonsense statement. I don't claim _anything_ about DB's extensions. I report what has been written in multiple ICCA articles, in multiple books, and things discussed at several ACM tournaments with several others listening on. So forget this "it does a lot less than I claim" unless you want to claim that Hsu and company are making this stuff up. Of course then they somehow beat Kasparov with only a simply 11 ply search, if we listen to you? and that is _poppycock_. _NOBODY_ is going to beat kasparov with an 11 ply search as we are doing. And I mean _NOBODY_. > >We see this blowing up the search in older King versions >very good. I've had it in DIEP too. Also Genius used to >have big problems at depths above 11 ply, though i didn't >check how genius6 is searching. can't imagine it changed. Just because it doesn't work for you, doesn't mean it doesn't work for them. I used singular extensions in CB and didn't see this branching factor increase. Bruce uses a version he developed. He isn't seeing any serious "blow-up". Maybe I (and they) spent more time studying how it works than you have? It makes no sense to dismiss what you don't understand or can't get to work. Just because _you_ can't get it to work doesn't mean others can't... An important lesson to remember... > >Zarkov is doing threat extensions and also gets blown up above 10 or >11 ply. > >branching factors doing the extensions you described deep blue is >doing is gonna blow its search. Didn't for CB, didn't for Ferret. Didn't for DB either, based on their results... > >I know you don't have that experience yourselve, but it's easy >to experiment with it if you are ready to burn a few billion nodes >a search to test it out. What on earth do you mean? I have run _huge_ searches on the Cray in years past. With SE and without. I know _exactly_ how it affected my search. It cost me about 1 ply. My branching factor stayed fairly constant.. > >If the opposite is true: that they don't have such a bad b.f. above >depths of say 11 ply, then DB doesn't extend much. you are doing A->B X->Y so A->X. I don't see how you can make that leap of faith. Particularly I_cant_do_it -> nobody_can_do_it. I don't follow that deduction either... > >Personally i would bet they didn't experiment with the full blown machine >much either to searches deeper than tournament level... ...it was said >by the PR department of big brother to have been assembled ONLY to play >kasparov... ...and that they had problems during the games it crashing >against kasparov once because of this hastely assembly... This is definitely a problem... but they ran DB junior for _long_ searches so they had little unexpected search behavior... > >Make your choice... > >Vincent > >
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