How Many Games of Chess: Exact answer given!

[tim werner]

>From: Eli Brandt <ebrandt at jarthur.cs.hmc.edu>
>There are a finite number of legal positions in chess.  If any
>shows up a third time, the game is over.  Thus we have a bound on
>the length of a legal chess game.  Hence the number of games is
>finite, and we don't have to quibble about whether it's countably
>or uncountably infinite.

Since this is the second time this has shown up here, I must clarify it by
saying that it is only a draw when the pieces are in the same position with
the same person to move for the third time.  It is possible to repeat the
position but change the opposition, which constitutes a different
situation.

tw