ExpertUsefulness: Low
Remote Pairs
A chain of bi-value cells all sharing the same pair {X,Y}. Alternating X/Y along the chain means the two ends are opposite, so any cell seeing both loses both candidates.
✕
An alternating {X,Y} chain; a cell seeing both ends loses both digits.
patterneliminatesolved
How to spot it
- 1Link bi-value {X,Y} cells that see each other into a chain.
- 2Colour them alternately X and Y along the chain.
- 3Any cell that sees both an X-end and a Y-end can't be X or Y.
When to use
When several identical bi-value cells thread across the grid.
Common mistake
Breaking the chain by including a cell with a third candidate.