Whips, handcuffs . . . sudoku? When you're in the mood for some masochistic pleasure, this variant of the popular puzzle will satisfy your desires. Each 10x10 grid is divided into ten regions of 5x2. Play like regular sudoku, except using numbers 0-9. Then comes the twist: each sudoku also has five 10-square grey regions to complete—a total of 50 squares of grey.
Mr. Riley is a software developer at Fairfield Language Technologies, and the author of numerous computer programmes that analyse variants of sudoku puzzles. Dr. Taalman is a professor of mathematics as James Madison University. Her research interests include singular algebraic geometry, knot theory and open questions about the mathematics of sudoku and other puzzles.
