PlaySudoku.us
Medium · Puzzle #144
9
2
3
4
3
8
9
5
2
6
4
3
8
7
7
4
2
9
6
8
2
5
8
7
1
5
3
9
6
7
4
5
3
2
6
4
Set theory provides the formal foundation for Sudoku's rules: each digit must appear exactly once per set.
Set theory provides the formal foundation for Sudoku's rules: each digit must appear exactly once per set.
"A theory that is not refutable by any conceivable event is non-scientific." — Karl Popper
"A theory that is not refutable by any conceivable event is non-scientific." — Karl Popper