Glossary

A row pattern that relies on a single rule (no-three, balance, or markers) to constrain the row.

A chain reaction where placing one symbol provides enough information to deduce another, which in turn deduces another, and so on.

A single square on the grid. Each cell holds either a sun or a moon.

The opposite symbol: sun is the complement of moon, and vice versa. Swapping every symbol in a valid row produces another valid row.

A row pattern that combines two or more rules to constrain the row.

Any rule that restricts which symbols can go in a cell. The three main rules and deductions from other cells are all constraints.

A row where at least one empty cell can be determined from its constraints alone, without information from crossing lines.

The boundary between two adjacent cells, where a marker may appear.

A constraint symbol on an edge: = (same) or × (different).

A recognizable arrangement of constraints within a row that narrows the possible solutions. Patterns let you place symbols by deduction rather than by trial and error.

A horizontal or vertical line of cells. For simplicity, "row pattern" describes patterns applicable to either rows or columns, since the same logic applies in both directions.

A row where none of the empty cells can be determined from its constraints alone. Solving requires information from crossing lines.