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Subject: Re: Never Say "Impossible"

Author: Robert Hyatt

Date: 06:47:34 05/11/01

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On May 10, 2001 at 09:43:18, Graham Laight wrote:

>On May 10, 2001 at 09:27:58, Robert Hyatt wrote:
>
>>On May 10, 2001 at 00:35:50, Uri Blass wrote:
>
>>>10^50 is an upper bound of the number of the legal positions(2 positions are the
>>>same if the pieces are in the same places and both sides have the same right to
>>>castle and the same rights to capture by the en passant rule).
>>>After less than 10^50 moves the same position happens twice
>>>
>>>If you can mate in 10^50 moves the game contains a repetition of the same
>>>position twice.
>>>If you can win with repetition you have a shorter win without repetition.
>>>
>>>It means that the problem of finding if a position is a draw or a forced mate is
>>>solvable in a finite time even without the 50 move rule
>>>
>>>Uri
>>
>>
>>Actually 10^50 simply means chess will never be solved.  That is getting very
>>close to the number of atoms in the universe.  How are you going to store that
>>information?
>
>No need to. Franz Morsch's Saitek Kasparov Travel Champion 2100 plays a strong
>game with only 2 Kb of memory. Much of that space will be needed for storing
>settings + move history. Clearly, it's not storing much information about the
>game tree.
>
>>and I am not convinced 10^50 is the right number.  There are positions and there
>>are positions...  the history (or move path) to a position is just as important
>>to its identity as is the location of each of the pieces.  Because without this,
>>repetitions and 50-move rule won't work at all.
>
>Uri's point was that if any given position is repeated, you can get to any
>subsequent position more quickly by removing the moves from the previous
>occasion the position occurred to the current one.
>
>-g


How will you know they are repeated if you don't store them?

:)



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