Author: Robert Hyatt
Date: 17:10:07 01/06/98
Go up one level in this thread
On January 06, 1998 at 17:30:40, Don Dailey wrote: > >Hi guys, > >Here is my take on Deep Blue and it's algorithms. First of all their >approach is based on lots of hardware which gives them a HUGE problem. >If something is wrong with our software we quickly fix it. If something >is wrong with their hardware they have a huge problem that will take >months to get to the next version. So there is a lot of flexibility >we take for granted that they do not get. What they have done is very >impressive indeed and took a great deal of engineering talent. don't take this "too" far. Much of what they do was microcode, and I doubt this has changed, so that many things can be changed. Also, they use the chess hardware out near the tips. The main search is done on the IBM SP. IE they look a lot like Crafty, the hardware handles the last N plies in a simplistic manner, plus the capture search. The SP (software) handles the first M plies, does the singular extension stuff and everything else they do. They wouldn't need to modify the search in the hardware very often. The evaluation is already programmable, so that can be changed easily and often without modifying the hardware at all... > >As far as the classic question about how would they do against the >best micro's on equal hardware? First of all it's not easy to define >what equal hardware is at all. But I'll take a stab and give you >my sense of the issues involved. > >Let's use REBEL as representative of the best software available. >If you scaled Rebel up to do the same Nodes per second as Deep Blue >there would be no contest, Rebel would be a HUGE favorite. I *totally* disagree. I'd peg DB's evaluation at being approximately 100X more complex than Rebel's based on Ed's current NPS rate. Don't forget the match that caused so much discussion where a single DB processor running at 100K nodes per second really smacked Rebel and Genius 10-0 in Hsu's lab. So you are *way* off base here. *way* off... > >But this is hardly a fair comparison, Rebel is a SERIAL program and >is clearly more efficient than a parallel program which tends to look >at many extra nodes to do the same amount of effective processing. > >So let's "pretend" we can run the pure Deep Blue algorithm in SERIAL >mode and match up both Rebel and Deep Blue, let's say 2 million nodes >per second (and equal hash tables.) > >The winner? REBEL wins again! But we are still being quite unfair. >Deep Blue is forced to accept compromises and inflexibilities that >REBEL does not have to deal with. It's quite certain that many design >choices were optimized for the exact approach each side was using. >From Deep Blues point of view, the stuff in Rebel would be wrong to >attempt to implement in Deep Blue. So far as I know, there are *no* compromises in DB. They have done *everything* they wanted... evaluation, attack detection, threat detection, I mean *everything*... Again, you are taking your knowledge of Rebel, but comparing it to almost no knowledge about DB. That gadget is *far* more sophisticated than anything else currently playing chess. Not just faster, but smarter as well. > >An example of this will suffice. Until recently Deep Blue could not >even pick up repetition in the hardware portion of the search. No micro >program would dare leave this out, it's a bad idea. But at the time >choosing to leave it out seemed right for Deep Blue because it added >too much complexity to the chips that did the end node searching. >When we played them in Hong Kong they were quite afraid we might get >a draw (we did not) because there were long checking lines for us. >They were noticably disturbed by the possibility. Guess again. Crafty doesn't catch repetitions in the q-search, because they are *impossible* in my q-search, which only includes captures and promotions. Ditto for Ferret. We're both doing reasonably well. They have handled repetitions correctly since Deep Blue started playing. The older Deep Thought and "deep blue prototype" had that bug, if you call it that... but it wasn't a serious issue. > >Well since then they have corrected this problem but there was no >easy fix. It took a complete re-engineering of the chip and probably >at least a YEAR or more to go through the whole cycle. > >The real bottom line here is that it is almost silly to compare the >two programs except on absolute strength. Deep Blue could probably >not hold up MOST of top micro's if you tried to equalize everything >in this manner but it's no reflection on the Deep Blue team. In >every way (except raw speed) the Deep Blue team is handicapped so you >can not expect them to compete with the highly tuned micro programs. Don, your lack of hardware design experience shows here, no insult intended. They can do *anything* they want, and with "silicon compilers" it is trivial to do for them. Hardware design is now more like programming than designing. But there are fewer compromises in DB than in the micro programs. IE I'd *love* to design such a chip, because my rotated bitmaps would be perfect for that type of hardware, because I could do the rotation in 0 cycles. In fact, a "crafty on a chip" would not be difficult to do, if there was funding to pay the bill. But your "DB is full of compromises" is simply off-base. You ought to poke Hsu over the phone or via email to get a better feel for what they have done. It's most impressive... and not just because it is fast... They have it *all*... > >Would you compare a world class human sprinter to a cheetah and say >how fast would the Cheetah be if it were only human? > >So does Deep Blue suck? In rating points per node searched, YES. >In absolute strength of course NOT. It's unclear (to me) if they >are much better than the very best micro's but I'm pretty sure it >would win a long match against any of them (this year anyway.) > >Deep Blue's performance seems to be about as good as the top micro's >based on the few tournaments it's played in and the close (but very >short) match against Kasparov is a good indication that it's quite >strong. This I don't follow. What micro has beaten a GM in 40/2? In a match of 40/2? What micro has beaten as many GM's as DB in anything (excepting blitz, where most micros do ok at times)... > >Sorry Bruce, I know you didn't want to hear about this! I carefully >avoided singing their praises or saying they sucked! > >- Don
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.