Hello,

Follow-up to the recent discussion here: I've improved my Sudoku solver 
and released it with some documentation

http://www.eleves.ens.fr/home/frisch/sudoku.html

It was able to deal in reasonnable time with all the 3x3, 4x4 and 5x5 
grids I could find (often <10ms for 3x3 grids). Some difficult puzzles 
are included in the distribution.

   Alain