Author: Robert Hyatt
Date: 06:55:57 01/21/00
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On January 21, 2000 at 00:08:13, Michael Neish wrote: >On January 20, 2000 at 23:19:41, Dann Corbit wrote: > > >>Hyatt & Heinz both did "goes deep" experiments that show no matter how deep you >>look, you never stop finding improvements. And each new ply is of approximately >>the same value as the one before it (but much harder to calculate). >> >>GM's, also, can be wrong in their analysis. So what is the best move from some >>board position? Nobody knows. On the other hand, you *can* rigorously say that >>for an examination of all the positions up to n plies forward, some move is >>better than others (assuming you can come to agreement on how to calculate >>piece, positional, and other value factors consistently). > >Well, there's only a limited number of moves in a position, and many of these >are probably obviously bad. I suppose what you mean by finding improvements is >that you can keep switching between possible candidate moves as you search >deeper, right? Maybe the computer switches back and forth between axb5 and Qb6 >as it thinks. I remember reading in some paper that as you get very deep errors >start to creep in the evaluation, so that after a certain depth, if there is no >definite tactical objective, you cannot trust the evaluation at all. I have the >reference to the paper at home, which I can give you if you're interested. The >author said that Chess programmers tend to ignore this phenomenon, which is >negligible at shallow search depths but becomes more and more serious with >increasing depth, but that it's there all the same. But we're digressing. > Who wrote that? My initial thought is 'nonsense'. Otherwise a 12 ply search would play positionally worse than an 8 ply search. And I don't see that at all. I can't imagine a 'barrier' that if passed, causes your eval to suddenly start producing nonsense scores... so it has to start immediately and would be apparent starting as we go from 1 to 2, and should be really apparent by the time we get to the usual 13-14 plies in the middlegame... >By the way, how about the move Qb6, which (I think) is what Kasparov thought >every honest computer should play. Is it some sort of trap that Kasparov had >laid, which would eventually lead to a draw, or does it also win for White? If >Qb6 is good enough to win, then why would the IBM team override a winning move >with another more elegant winning move selected by a grandmaster? Mainly because it provides a good excuse. :) > >Cheers, > >Mike.
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