View source for Sudoku-X

'''Sudoku-X''' is one of the better known [[Sudoku Variations]]. It is similar to a standard [[Sudoku]], but both [[diagonal]]s must also contain digits 1 through 9.

Because the diagonals significantly reduce the number of [[Unavoidable Set]]s, the puzzle can contain less [[given]]s than a standard Sudoku. Also, the diagonals create opportunities for additional [[techniques]], such as [[Skewed Fish]] ([[Triangular Connection]], [[Crossover]], [[Double Crossover]], [[Finned Double Crossover]], [[Skewed Swordfish]]), [[Multiple Crossover]], [[Weak Link Square]] and [[Skewed XY-Wing]].

The diagonal [[constraint]]s are also used in several other variants and sizes. For example, the [[Killer]] variant can be combined with diagonal constraints to form Killer-X. A more extreme example would be [[Clueless]]-[[Shaolin]]-X.

Below is one easy Sudoku-X puzzle. It requires only [[single]]s and one application of [[Naked Pair]].

[[Image:SudokuX.png]]

== Minimum Number of Givens ==
[[User:Ruud|Ruud]] has a [http://www.sudocue.net/minx.php collection] of Sudoku-X puzzles with as few as 12 [[given]]s. However, the actual minimum number of givens required for a valid Sudoku-X puzzle is not known.

== See Also ==
* [[:Category:Sudoku-X]]
* [[Windoku]]
* [[Asterisk]]

[[Category:Sudoku-X]]