Author: Dann Corbit
Date: 23:30:17 01/20/00
Go up one level in this thread
On January 21, 2000 at 02:24:15, Peter Kappler wrote: >On January 21, 2000 at 01:16:56, Will Singleton wrote: > >>On January 20, 2000 at 22:25:42, Peter Kappler wrote: >> >>>>I think that more speed is not the answer, because at 15+ plies, you're already >>>faced with with seriously diminishing returns per extra ply. Any tactics that >>>exist in the position (or that a human would ever have a prayer of finding) have >>>long since been discovered, so the computer's positional evaluation starts to >>>become the limiting factor. And computer chess still has a long, long way to go >>>in that area. As you've stated yourself in other threads, the GMs are getting >>>better at exploiting these weaknesses. >>> >>>--Peter >> >>I'd have to disagree here. I don't see the diminishing returns as depth >>increases. There are certainly tactics present at any depth, and one can >>imagine a positional advantage at 18 ply that couldn't be seen at 17. >> > >Imagine a slow chess program that can only search 5 plies in the middlegame. >Even simple combinations will be beyond its search horizon. Now, take the same >code, and put it on a much faster machine that can search 8 plies. The 8 ply >machine will destroy the 5 ply machine. It won't even be close. The 8 ply >searcher would probably win every game. At shallow depths, tactics are >everything. > >Now lets imagine the same scenario, but with 15 plies vs 18 plies. The 18 ply >machine will be stronger, but I think the games would be very closely contested, >with lots of draws, and a few wins for the 18 ply machine. The concept I'm >trying to illustrate is something that others have described as a "tactical >sufficiency threshhold". It's a point (depth) beyond which forced tactical >sequences are extremely unlikely. > >In short, if you compare an n-ply searcher to an n+3 ply searcher, the >difference in strength will certainly diminish as n grows. This statement is false, according to experimentation. Both Robert Hyatt and Ernst Heinz have shown experimental evidence that there is *NO* drop-off in value for additional plies. See the "Crafty Goes Deep" and "DarkThought Goes Deep" for experimental proof of the opposite of what you just said. >>So, in the arena of comp vs human, speed is really the only answer. Or, more to >>the point, in the absence of improved algorithms, speed would still do the job. > >Speed always helps. Beyond a certain depth, I just think knowledge helps much >more. What is knowlege in this case except understanding of the future? That is *exactly* what additional plies of search give. Given enough depth, a tactical program would be thinking strategically. Imagine a program that gets 60 plies. It is thinking 30 full moves into the future. That, my good man, *is* strategy. There may be superior ways to achieve a vision of the future. I am not disputing that a knowlege based engine may have a clear advantage over brute force at some point. But additional plies never "wear off" as not only experimentation provides, but also simple induction.
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