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Subject: Re: Some Philosophical questions on the limits of Computer chess

Author: Sune Fischer

Date: 06:27:03 01/26/02

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On January 26, 2002 at 09:07:51, Albert Silver wrote:

>>>>Realisticly a 2800 player probably has a branchfactor of no more than 2, ie. he
>>>>is able to always choose the best or second best move (on average).
>>>>If the average game lasts 100 moves, then that is still 10^30 plausible games of
>>>>which only a handfull will be good enough against *perfect* play.
>>>>Poor odds I agree with you :)
>>>
>>>You're presuming that anything other than one move, the best move, will lose
>>>forcibly to best play. I believe that more than one move is available to a
>>>non-loss thus perfect play would be often a flip of the coin between a few
>>>(perhaps three as I hypothesized in another post in the thread) moves. I have
>>>seen no evidence to suggest there is only one path to a non-loss and that a
>>>single path of perfect play is needed to avoid it. Everything we know whether
>>>from personal research or from the current tablebases suggests there are several
>>>paths. If this were accepted to be true, the question would be whether the 2800
>>>player is incapable of hitting on _one_ of these non-losing moves (according to
>>>perfect play).
>>>
>>>                                      Albert
>>
>>You could interpet in an similar way; there is a 50% chance of the 2800 chooses
>>a move that is *good enough*.
>>It was just an estimate, probably way off :)
>>
>>Suppose that a *correct* move is done with 95% certainty (on average) and that
>>the average game length is only 60 moves, then he has a 0.95^60 = 4.6% chance of
>>a draw!
>>
>>This is perhaps more realistic?
>>
>>-S.
>
>Well, a few things come to mind. One is that there would be more than one
>correct move to hit on.

Yes, and that why I rephrased it to be a *correct* move rather than *the best*
move, by *correct* I mean a move that isn't losing.


>Second that I wasn't aware that his chances changed with
>each move, so I don't think that the longer the game the worse his chances. Give
>a 2800 player a dead equal dry game and I don't think he will suddenly be in
>danger of losing just because it can take 40 moves to trade off the pieces and
>pawns and play the endgame to the end. There is more to chess than probability.
>
>                                     Albert

What I meant was, that at every move he has a 5% chance of _not choosing the
correct move_, ie. he "blunders" by playing inaccurate.
That is an average percentile taken out of the blue of cause, but the tablebase
test could give us a hint whether we are talking 95% or 50%, it would allow us
to calculate the rating of a perfect player, which was the goal I believe.

-S.



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