[casual_games] Sudoku difficulty

[Charles Parcell]

This actually is spawning from another list I am on where we are talking 
about Sudoku puzzles. the question has been posed, how do you rank a 
Sudoku puzzle as simple, or difficult?

We are discussing generators. The approach has been to generate a solved 
puzzle first and then remove numbers from there. In this removal process 
it is assumed that different formulas would be applied to generate an 
simple or difficult puzzle. There are two thoughts going on around this. 
First is the number of empty locations within a puzzle. The second 
thought is the number of start points for solving and "chaining" solutions.

Since this is a casual game list and Sudoku is a casual game... I assume 
that this is not an inappropriate e-mail.

Charles P.