Author: Robert Hyatt
Date: 10:30:20 06/19/01
Go up one level in this thread
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.
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