Coloring
An advanced technique that traces conjugate pair chains for a digit using two alternating colors to find contradictions.
Simple Coloring traces chains of conjugate pairs (units where a digit has exactly 2 candidate cells) for a specific digit, alternating between two colors. Contradictions (same-color cells in one unit) or cross-eliminations (a cell seeing both colors) allow candidate removal. It generalizes X-Wing to arbitrary chain lengths.
Conjugate Pairs and Chains
A conjugate pair exists when a digit has exactly 2 candidate cells in a unit. These cells are mutually exclusive. Tracing this exclusive relationship through linked pairs and alternating colors A and B visualizes the logical structure of the entire chain.
Two Elimination Patterns
Same-color contradiction: if two cells of the same color share a unit, that color is entirely wrong. Cross elimination: if a cell sees both a Color A and a Color B cell, the digit can be eliminated from it, since one color must be correct and either way that cell is excluded.