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Subject: Re: Never Say "Impossible"

Author: Robert Hyatt

Date: 06:27:58 05/10/01

Go up one level in this thread


On May 10, 2001 at 00:35:50, Uri Blass wrote:

>On May 09, 2001 at 22:01:31, Robert Hyatt wrote:
>
>>On May 09, 2001 at 19:20:18, Uri Blass wrote:
>>
>>>On May 09, 2001 at 18:41:43, Robert Hyatt wrote:
>>>
>>>>On May 09, 2001 at 13:33:21, Uri Blass wrote:
>>>>
>>>>>
>>>>>The rules of chess say that the if a game takes more than 9999 half moves both
>>>>>sides can ask for a draw by the 50 move rule.
>>>>>
>>>>>If you do not assume that both opponents are stupid in your calculation then it
>>>>>is clear that one of them will ask for the draw so you can assume for practical
>>>>>purpose that it is a draw.
>>>>
>>>>
>>>>Suppose it is a game, for "winner takes all" where if it is drawn, nobody
>>>>gets a cent?  Will you claim the 50-move draw there or will you keep trying
>>>>to win the pot of gold?
>>>>
>>>>Then you see why I say that unless someone proves that chess is won for white
>>>>or black, which is not going to happen for a few thousand centuries, then I
>>>>will keep playing.  Until the end of time if needed, hoping for my opponent to
>>>>make a mistake...
>>>>
>>>>
>>>>>
>>>>>I can prove for a bigger constant that there is not.
>>>>>The shortest mate is of less than 10^100 plies because every game of 10^100
>>>>>plies include repetitions and if there is a mate there is a shorter mate with no
>>>>>repetitions.
>>>>>
>>>>>Uri
>>>>
>>>>
>>>>That doesn't make the length of all possible games finite however.
>>>
>>>It is totally irrelevant.
>>>The point is that even without the 50 move rule after enough plies searching
>>>deeper is not going to give better results.
>>>
>>>If you find a forced mate for one of the sides it is clear that searching deeper
>>>is not going to help.
>>>
>>>If you do not find a forced mate for one side then it is clear that the position
>>>is drawn and searching deeper is not going to help(programs do not assume that
>>>the opponent will do a mistake in their search).
>>>
>>>Uri
>>
>>
>>Please prove that KQQQ vs KQQQ is drawn or won for each case.  Note that we
>>declare the 50-move rule is not in use.  How do you decide when to declare a
>>position drawn?  No captures in 50 moves?  I'll be happy to show you a 5 piece
>>position where a forced mate happens _well_ beyond the 50 move rule.  So how
>>do you stop?
>
>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?

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.




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