PlaySudoku.us
Hard · Puzzle #235
5
1
9
2
5
7
9
9
8
3
3
9
5
6
3
2
5
8
1
6
8
4
7
3
5
2
8
8
9
4
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.