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Pairs

Two of a kind side by side, and both ends are spoken for.

The rule of thumb: Two matching symbols side by side: the cells on either side of them take the other symbol.

Find two suns touching in a row or column (or two moons). A third sun on either end would make three in a row, which the rules forbid.

So both neighbors of the pair take the other symbol. A pair against the edge of the board has only one neighbor to fill.

Every symbol you place is a chance for a new pair, so Pairs feeds itself. These first practice boards fall to Pairs alone.

Where to look: Any two matching symbols touching. Each time you place one, check its row and its column, in both directions.

Worked example

A real position from a board that needs Pairs. Purple: what the reasoning rests on. Dashed: the cell in question. Green: what it proves (“this cell” in the text).

Row 1 has two moons touching (purple). The dashed cell next to them is still empty.

Row 1 has two moons side by side, so the cell next to the pair must be a sun. A third moon would make three in a row.

Practice it ↓