Author: Robert Hyatt
Date: 10:28:31 06/29/98
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On June 29, 1998 at 12:39:13, Bruce Moreland wrote: > >On June 29, 1998 at 00:30:49, Robert Hyatt wrote: > >>On June 28, 1998 at 23:48:43, Bruce Moreland wrote: > >>>But I don't think that the DB project proved anything at all about search or >>>evaluation techniques. I don't think that you can look at the project from our >>>point of view as outsiders, and say that any technique is shown to be good or >>>bad because of what they did. Anyone who tries to say the project proved >>>anything ends up making arguments based upon painfully little real evidence, >>>most of the evidence is anecdotal *at best*. > >>perhaps to you. Unfortunately, I have had the opportunity to sit across >>the board from them, with a program of known capabilities (Cray Blitz) and >>have seen first-hand what they can do. I don't know of *any* program that >>has only lost 2-3 games in 10 years of ACM and WCCC tournaments. That is >>a *huge* record. I don't know how good they are, to be sure, but I have a >>good idea of what Cray Blitz can do, and they are certainly better than it. > >I am not challenging the record of DT. > >I am merely stating that it can't be said that null-move is bad just because DB >doesn't do it. > there I'd agree. They are so much faster/stronger than the rest of us, that whether they use null-move or not is probably inconsequential. I believe that null-move would make them even stronger, but Hsu has this "perfection" syndrome that refuses to accept any error at all unless it is unavoidable. With null- move, you instantly agree to accept errors, in return for more depth that might catch errors you didn't agree to accept. >When a giant comes onto the battlefield, with an 12 foot section of log as a >weapon, and knocks everyone's head off, this shouldn't cause everyone else to >drop their swords and pick up sticks. The lesson to the little guy is that you >should get big. The giant gets no lesson here, since he won, and he'll be back >next time with a bigger log. > >When you introduced Crafty, you had some problems because you didn't do micros, >for instance you had some big memcpy's that slowed you down on a micro, but >which didn't make any difference on the Cray. > >But there were some other changes you made because the changes made you stronger >on the micro platform. For instance, you went to null move R=2, and you stopped >extending so much. > >I don't think you would have done this if you didn't have competition that could >score points against you. If you were running on something twenty times faster >than the rest of us had, you'd be doing stuff that you needed to be doing in >order to waste wimps. You could talk about exploiting pruning mistakes in the >slower programs, you could extend a lot in order to superset the slower machines >while still yielding the same search depth. without a doubt correct, although I probably lean a little backward toward Cray Blitz now, since parallel processing has boosted my speed enough, I'm now trying to find time to investigate things that I found useful in CB, like singular extensions, for one example. I'd like to one day try null-move R=2 on CB, but it would be *very* difficult to do since all that stuff is in assembly language. But I'd like to know how that affects the thing since I *never* tried it, never even tried recursive null-move in fact.. > >And oh yeah, as I have stated in an old post, you'd be winning all of these >games, so by definition everything you did would be working right. You'd feel >good about your eval function and your search. Who changes stuff that they feel >good about? > >But if someone came along who could offer you competition, you would have to >change, and I bet we'd see null move R=2 again, and we'd see fewer search >extensions, and I bet you'd do some muttering about your eval. > >This is my speculation about DT. I doubt they were placed under much >evolutionary pressure, I mean, if you can effectively wield a 12-foot log >section, what is going to stop you? they had a lot of pressure from us. We were never slow, and almost beat them the first time we played them, but a cute SMP bug made us avoid a outright winning move that they were expecting, and we were going to play, until the last minute. In fact, they never "overwhelmed" us in speed, since they were doing 2-3M nodes per second in deep thought II, while we were only doing 1/4 of that or so at the time. As a result, their stick wasn't "that big", only a factor of 4 or so. But other things were certainly working for them in our games, like SE for one. > >DT/DB is a good source of ideas, but if you try to emulate them on a computer >that anyone can afford, something really bad will happen. > >And I think it makes good sense to ask if their project would be a lot different >if they'd had someone who put them under some real evolutionary pressure. > >If you went back to the Cray again, would you really use null move R=1 (or take >it out entirely) and tons of expensive extensions? > >bruce I'd obviously try R=2. At the time, it wasn't being done. And R=1 caused enough grief in some cases. But the other extensions I'd likely keep, because we could afford them and they worked well with our eval. IE no pin analysis because we could add plies to the search for cases that tripped our "pin analysis trigger." I don't do those things (yet) although I plan on trying a few as time goes on... problem is, my "to do" list never gets shorter. :)
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