Article View: sci.logic
Article #394Re: "Solvability" in Chess
From: sven hauptfeld
Date: Mon, 28 Sep 1992 04:30
Date: Mon, 28 Sep 1992 04:30
33 lines
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2278 bytes
I want to point out that the 'optimal play' as understood in the solvability problem and 'optimal play' in actual game may be *very* different. When we try to solve a game, we ask if it is possible for either side to force a win against perfect play (i.e. against any reply). The optimal strategy in this case is minimax strategy: if we can force a draw, but not a win, we must not play a move which wins against all but one reply, against which it loses. The optimal strategy for *playing* the game is the same *only* if one side can force a win and we are playing that side. Then we simply play the moves which win against all replies. But what if neither side can force a win from the initial position? (This may well be true for chess, at least I'd bet on this outcome if the solution were practically achievable.) Suppose the supercomputer that has solved the game challenges the World Champion? If it consistently applies minimax strategy, and the Champion never plays a losing move, all games end in a draw and the Champion retains the title! Therefore, the optimal algorithm for winning games is considerably different! Incidentally, this means that the discovery that the initial position is a forced draw would be good news for all the people who fear the loss of 'uncertainty' in chess: it would mean that one must take risks to win! Sven P.S. The last statement is oversimplified. It is true only under some additional assumptions. Namely, it is possible that the initial position is a draw with best play, but that (say) white has winning paths in which best play by black still leads only to a draw, i.e. that white doesn't have to risk.
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Newsgroups: sci.logic,sci.math,rec.games.chess Path: arc1-ca.pugleaf.net!sparky!uunet!cs.utexas.edu!asuvax!ncar!uchinews!ellis!hau4 From: hau4@ellis.uchicago.edu (sven hauptfeld) Subject: Re: "Solvability" in Chess Message-ID: <1992Sep28.043001.26295@midway.uchicago.edu> Sender: news@uchinews.uchicago.edu (News System) Reply-To: hau4@midway.uchicago.edu Organization: University of Chicago Computing Organizations References: <1992Sep24.122426.28445@access.digex.com> <Bv34IL.E5w.2@cs.cmu.edu> <CONVERSE.92Sep27014123@sloth.uchicago.edu> Date: Mon, 28 Sep 1992 04:30:01 GMT Lines: 34