[Retros] A single integer N = a complete chess game

[François Perruchaud]

The most efficient way to code a single move is to give its number in a 
list of moves given by a program.
Using a program of mine, a Ruy Lopez is :
13 (14th move of 20 - 5 bits) = 1.e4
9 (10th move of 20 - 5 bits) = 1...e5
13 (14th move of 29 - 5 bits) = 2.Nf3
15 (16th move of 29 - 5 bits) = 2...Nc6
7 (8th move of 27 - 5 bits) = 3.Bb5
No separator is needed.
(I didn't *really* use a program for that)

Coding and decoding is easy (theorically and pratically) if you have the 
good program (or the good algorithm) to give the list of moves. Any 
algorithm can be used.
Of course, you can give a code for a whole game that is more efficient 
than the list of moves (see Mark's trick).

FPC