XY-Chain
Expert
A chain of bivalue cells (each with two candidates) linked so a candidate passes from one to the next. When both ends of the chain offer the same letter, that letter is ruled out of every cell that sees both ends.
Expert
A chain of bivalue cells (each with two candidates) linked so a candidate passes from one to the next. When both ends of the chain offer the same letter, that letter is ruled out of every cell that sees both ends.