Remote Pairs
A chain of four or more bivalue cells all holding the same {X, Y} candidates. The endpoints hold OPPOSITE digits — any cell that sees both endpoints loses both X and Y.
Advanced sudoku technique
What it is
A Remote Pair is a chain of an EVEN number of bivalue cells (4, 6, 8, ...), all sharing the same two candidates {X, Y}, where consecutive cells in the chain share a unit (row, column, or box). Because each connection forces alternating X/Y assignments along the chain, the two endpoints must hold OPPOSITE values — one endpoint is X and the other is Y (we don't yet know which is which). Therefore any cell that sees BOTH endpoints can't be X (the X endpoint blocks it via shared unit) AND can't be Y (the Y endpoint blocks it). Eliminate both digits.
Want the full theory?
The Remote Pairs guide on Sudoku247Wiki walks through the logic step by step, with worked examples, diagrams and FAQs.
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