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Empty Rectangle
When a box's candidates for a digit fit in one row plus one column (an "L", the hinge), a conjugate pair crossing the hinge forces an elimination at the far intersection.
There's a move in the top-left box.
When a box's candidates for a digit fit in one row plus one column (an "L", the hinge), a conjugate pair crossing the hinge forces an elimination at the far intersection.
There's a move in the top-left box.