PlaySudoku.us
Hard · Puzzle #811
9
8
4
7
5
1
9
8
4
2
6
3
4
5
8
2
7
9
5
2
3
4
9
7
3
6
4
9
8
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.