High Corner Clue
A 3 in a grid corner forces both outer sides to be lines, because the two inner sides alone cannot reach 3.
How it works
- 1The bottom and right sides meet at the board's corner dot, which has no other edges. They must therefore match: both lines or both blank.
- 2If both were blank, the cell would have only its top and left sides available and could never reach its clue of 3.
- 3So both outer sides are lines.
- Edge the technique adds
- Cells that establish the pattern