PlaySudoku.us
Hard · Puzzle #73
5
1
4
8
7
7
9
5
3
8
4
7
9
6
4
2
1
1
3
8
4
1
2
6
5
4
3
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.