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Cage no-repeat

A digit confined to one cage within a unit leaves the cage's other cells. hard

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Digit 4 fits nowhere in its unit except the tinted cells of a single cage. A cage never repeats a digit, so the cage's cells beyond the unit (R4C7) lose it.

If every place a digit can go within a unit falls inside a single cage, that cage must hold the digit there. Since digits never repeat in a cage, the cage's cells outside the unit lose the digit.