Does every validly posed Sudoku have at least one solution? If not, what is the minimum number of givens for it to be unsolvable? - Quora
Did you solve it? Le Sudoku français est arrivé! | Mathematics | The Guardian
Sudoku Archives - Uni-Presse
For a completed 9x9 Sudoku puzzle, what is the minimum number of checks needed (e.g., valid horizontal or vertical lines or 3x3 boxes) to be absolutely sure that the solution is in
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