Remote pairs: alternate the same pair along a chain

Remote pairs form a chain of bivalue cells that all contain the same two digits. Consecutive cells must see each other.

Key idea

An even chain gives opposite endpoint states. A cell that sees both endpoints can contain neither digit from the pair.

See the move, step by step

Follow a 5/7 chain from R1C1 to R3C3.

Step 1 of 4

Locate cells that contain exactly the same pair, 5 and 7, and can be connected through shared units.

Rows containing the chain

Step 2 of 4

R1C1, R1C6, R3C6, and R3C3 form an even chain. Adjacent cells must take opposite values.

Chain regionsAlternating remote pairs

Step 3 of 4

R2C3 sees R1C1 through box 1 and R3C3 through column 3, so it cannot be 5 or 7.

Remote-pair chainCandidates to remove

Step 4 of 4

R2C3 retains only its other candidates while the chain itself stays unresolved.

Remote-pair chainUpdated target

Count links, not cells: the endpoints must have opposite states. Confirm the target sees both endpoints before removing both pair digits.