PlaySudoku.us
Hard · Puzzle #190
4
8
6
3
2
7
1
5
9
3
7
1
9
2
3
4
7
9
4
5
4
6
5
2
3
4
1
2
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.