Remote Pairs

Remote Pairs is your gentle introduction to chain logic. It uses a run of cells that all share the same two candidates, linked so that their values alternate — and from that alternation you can make eliminations at the ends of the chain.

What is a Remote Pair chain?

Start with a naked pair — two cells with, say, {4, 9}. If another {4, 9} cell sees one of them, it's forced to the opposite value, and you can keep going: each new {4, 9} cell that sees the last one flips the value again. Follow such a chain and the cells alternate 4-9-4-9 along its length. Two cells an even number of steps apart hold opposite values — so any cell seeing both of them can hold neither 4 nor 9.

Step by step

1. Find a run of cells all holding the same two candidates, each seeing the next.
2. Trace the alternation. Values flip along the chain: 4, 9, 4, 9…
3. Look at cells an even number of links apart — they hold opposite values.
4. Eliminate both digits from any cell that sees both such ends.

Why it's a good first chain

Most chain techniques ask you to track several different digits as you hop from cell to cell, which takes practice. Remote pairs keep things simple: every link in the chain uses the same two candidates, so there's only one thing to follow. That makes it the ideal place to get comfortable with the idea that a run of linked cells forces a conclusion at its ends — the same idea that powers colouring and the longer chains beyond it.

Common mistakes

• Different candidate pairs. Every cell in the chain must share the same two digits — the moment one differs, the chain breaks.
• Odd separation. The elimination works between cells an even number of links apart; ends an odd distance apart hold the same value, which tells you nothing new.
• Chaining cells that don't see each other. Each cell must genuinely see the next — share a row, column or box — or the alternation doesn't hold.

Which Sudoku types is this best for?

The same logic applies across variants, but it pays off more in some than others.