Author: Robert Hyatt
Date: 19:14:47 06/19/01
Go up one level in this thread
On June 19, 2001 at 18:57:12, Bas Hamstra wrote: >On June 19, 2001 at 13:30:20, Robert Hyatt wrote: > >>On June 18, 2001 at 16:00:56, Bas Hamstra wrote: >> >>>On June 18, 2001 at 13:09:24, Robert Hyatt wrote: >>> >>>>On June 18, 2001 at 11:45:25, Bas Hamstra wrote: >>>> >>>>>On June 18, 2001 at 11:00:14, Ulrich Tuerke wrote: >>>>> >>>>>>On June 18, 2001 at 10:51:12, Bas Hamstra wrote: >>>>>> >>>>>>>On June 18, 2001 at 08:33:21, Ulrich Tuerke wrote: >>>>>>> >>>>>>>>On June 18, 2001 at 08:28:08, Bas Hamstra wrote: >>>>>>>> >>>>>>>>>On June 17, 2001 at 01:09:50, Robert Hyatt wrote: >>>>>>>>> >>>>>>>>>>On June 16, 2001 at 22:59:06, Vincent Diepeveen wrote: >>>>>>>>>> >>>>>>>>>>>Hello, >>>>>>>>>>> >>>>>>>>>>>From Gian-Carlo i received tonight a cool version of crafty 18.10, >>>>>>>>>>>namely a modified version of crafty. The modification was that it >>>>>>>>>>>is using a small sense of Singular extensions, using a 'moreland' >>>>>>>>>>>implementation. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>>Instead of modifying Crafty to simulate Deep Blue, why didn't you >>>>>>>>>>modify Netscape? Or anything else? I don't see _any_ point in >>>>>>>>>>taking a very fishy version of crafty and trying to conclude _anything_ >>>>>>>>>>about deep blue from it... >>>>>>>>>> >>>>>>>>>>Unless you are into counting chickens to forecast weather, or something >>>>>>>>>>else... >>>>>>>>> >>>>>>>>>I don't agree here. It is fun. Maybe not extremely accurate, but it says >>>>>>>>>*something* about the efficiency of their search, which I believe is horrible. I >>>>>>>>>think using SE and not nullmove is *inefficient* as compared to nullmove. We >>>>>>>>>don't need 100.0000% accurate data when it's obviously an order of magnitude >>>>>>>>>more inefficient. >>>>>>>> >>>>>>>>May be you are right, if the program is running on a PC. However if you can >>>>>>>>reach a huge depth anyway because of hardware, may be you can afford to use >>>>>>>>this, because it doesn't matter too much wasting one ply depth ? >>>>>>> >>>>>>>I don't see why inefficiency becomes less of a problem at higher depths. >>>>>>>Nullmove pruning reduces your effective branching factor to 2,5 where brute >>>>>>>force gets 4,5. So you could suspect at higher depths the difference in search >>>>>>>depths grows, starting with 2 ply, up till how much, 5 ply? >>>>>>> >>>>>>>Of course nullsearch has holes, but they are certainly not big enough to offset >>>>>>>a couple of plies, or none would use nullmove! In practice a n ply nullmove >>>>>>>search sees more than a n-2 ply BF search. >>>>>>> >>>>>>>Keeping that in mind, give Crafty 1000x faster hardware. It would search at >>>>>>>least 20 ply (normally 13 average according to Bob plus at least 7). I can tell >>>>>>>you DB does not search 18 ply BF. Therefore Crafty would in principle see more, >>>>>>>given the same eval. The SE thing only makes it worse. >>>>>>> >>>>>>>>I rather doubt that you can really learn something about Deep Blue this way. >>>>>>> >>>>>>>I don't see why not. He simply shows how inefficient their search is. Where does >>>>>>>Vincent's "emulated" search fundamentally differ from DB's, in your opinion? >>>>>> >>>>>>Except for the authors, nobody knows. That's the problem. >>>>>>We can't even be sure if they had some kinds of pruning. >>>>> >>>>>As far as I know they only pruning they did was futility in the qsearch. At >>>>>least they seemed to have told Bob Hyatt FP was a win, therefore the probably >>>>>used it. >>>> >>>>Obviously so. But what else did they use that we don't know about? IE how did >>>>they get their effective branching factor under 4.0? With so many unanswered >>>>questions, posing such a basically flawed experiment is really a waste of time. >>> >>>>>>If I got it right, their "engine" was a combination of software and hardware >>>>>>implemented stuff. So, you cannot just scale the crafty results by some factor >>>>>>and compare then with DB results. DB executed on a platform which is very >>>>>>different from todays PCs. >>>>> >>>>>But we can compare search model A and B and talk about it. >>>> >>>>But you don't know much about "B". Which means you have no idea how >>>>close "A" and "B" are. So you can "talk about it" yes. But you can't >>>>learn anything usefule from it. >>> >>>I don't know that exactly Vincent tries to prove, suppose the modified Crafty >>>does worse on all suites as compared to the normal Crafty and it loses all games >>>against it. In my case that raises the suspicion that, though DB was good, it >>>probably could have been even better. Hsu is not God, he doesn't know everything >>>and nullmove wasn't as popular back then as it is now. And Hsu had no >>>competition with comparable nps, else he would have learned it pretty fast. >>> >>> >>>Best regards, >>>Bas. >> >> >>First you do know that null-move was used in the early 1980's? I used it in >>the 1983 world championship tournament. It was suggested to me by someone that >>had already experimented with it after reading something by Don Beal. >> >>It was around. Hsu knew of it. Which means that if he didn't use it, he had >>other reasons than "not knowing about it". Hsu did have competition in NPS. >>In 1987 he was doing not quite 2M nodes per second. We were doing 1/2M >>ourselves. in 1989 he was still doing roughly 2M, we were doing about 1M on >>the C90 at the WCCC in Canada that year. >> >>IE he didn't have a huge NPS advantage against us. In 1987 we probably should >>have won, but didn't. From then on they were pretty convincing when we played >>them. > >Ok, at the time you had a nps that was not too far behind, did you try recursive >nullmove against them? If you didn't, he would have learned it if you did! If >you did, I have some more questions :-) > >Bas. I tried recursive null-move but didn't like it at the time. Of course, that was when we were doing 8 ply searches on the earlier crays... I never used anything but R=1 either, and never even tried R=2 back then. I am not sure but what the jury might still be out on "null-move". There might be better ways of doing forward pruning that are not widely known as of yet...
This page took 0 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.