PlaySudoku.us
Hard · Puzzle #172
1
9
5
4
2
7
5
1
3
2
6
2
7
6
5
3
7
4
5
1
6
8
2
3
6
1
9
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.