Author: Bruce Moreland
Date: 18:08:08 05/21/01
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On May 21, 2001 at 18:33:32, Ratko V Tomic wrote: >> I flip a coin 5 times and it comes up heads every time. >> Does that mean the coin is biased? > >It is not as simple as a coin toss. If all you extract out >of 100+ plies played in a game is the result (one of values >1,0.5,0), then you're wasting 99.9.. percent of available >information. You can play a single game against, say, a GM >and you will know a few moves after the opening that you're >dealing with a player much stronger than you. Or, playing >against a complete novice, you can again easily guess that >his/her rating is much lower than yours, even though not >a single game has been finished, and according to your >chess==coin_tossing theory, there is zero information >available. > >We have also all seen quite accurate ratings of programs >extracted after only few dozen next-move evaluations (e.g. >with well calibrated test suites). A single game has often >several times more positions that program has evaluated, >therefore the information is there even after a single >game to get the prgram's rating within a 50-100 points. > >The only model in which your coin tossing theory of chess >is meaningful is a mindless rating estimator taking in >only 1.58 bits of information per game (log2(3)), i.e. >the final game outcome and nothing else. Looking >through that kind of tiny pinhole anything you look at >will look random and senseless. The opposite is also dangerous. You can watch a game where one program completely dominates the other one, causing you to believe that you have enough information for an accurate assessment, and yet in the next game the roles are reversed. I think that there is a lot of information in a game, but I wouldn't trust anyone to extract it properly. The observer is watching a chaotic sequence and trying to extract meaning. A lot depends upon what the observer feels or believes. If you tune your TV to an unused channel and watch the static, your brain will create meaning. I don't believe in test suites as indicators of rating. The suites are created by selecting positions that return good looking results for a bunch of programs. Since they are designed to produce a specific result, it's hard for me to understand why people praise any suite's predictive powers. It's like a magician who puts a bunch of colored balls in a bunch of colored boxes, then covers his eyes and tells you which color box has which color ball inside it. Of course he'd know which box contains which ball. He's the one who put them in boxes. bruce
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