XY-Wing and Coloring both rely on chain logic - tracing implications through the grid until something must be true. But they operate at different scales. XY-Wing is a tight three-cell pattern with three digits; Coloring spreads through the grid following one digit's conjugate pairs. Understanding when each one applies is a major step into expert solving.
XY-Wing uses three cells: a pivot with candidates X and Y, and two wings sharing X-Z and Y-Z respectively. The pivot's value forces one wing to be Z, so any cell seeing both wings cannot be Z. The chain is short - exactly three cells - and uses three different candidates.
Coloring tracks one digit through chains of conjugate pairs (units where the digit appears in only two cells). You alternate colors A and B along the chain. If two cells with the same color see each other, that color is wrong everywhere. If a cell sees both colors, it cannot hold the digit.
XY-Wing is local - three cells, sometimes seven cells away from each other. Coloring can span the entire grid following dozens of conjugate links. This makes Coloring more powerful but also harder to set up. XY-Wing wins on simplicity; Coloring wins on reach.
Use XY-Wing when you spot bi-value cells with shared candidates. Use Coloring when one digit has many conjugate pairs but no obvious progress. In practice, XY-Wing applies first because bi-value cells are easier to recognize than chain structures.
Strong solvers use both. After XY-Wing eliminations create new conjugate pairs, Coloring may suddenly become available. Many expert puzzles require alternating between the two techniques as each unlocks new structure for the other.
Yes - Coloring requires building chains across many cells, while XY-Wing uses just three cells. Most solvers learn XY-Wing first.
Coloring covers more cases because it can chain across the entire grid. XY-Wing is faster to apply when the pattern exists.
Yes, especially in expert and extreme puzzles. Both techniques unlock structure for each other.
Not exactly, though both are chain techniques. XY-Wing uses three different digits in a fixed three-cell shape; Coloring tracks one digit through conjugate pairs.
A unit (row, column, or box) where a candidate appears in exactly two cells. Coloring chains link conjugate pairs together.
When you start tackling expert and extreme puzzles. Hard puzzles can usually be solved without either.
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