- ➊ Place a triangle (◢, ◣, ◤, ◥) in some white cells. Some
white cells may remain empty.
- ➋ A number in a black cell indicates how many sides of
orthogonally adjacent cells touches this cell. To a black cell without a
number an arbitrary number of triangle sides may be adjacent (maybe none).
- ➌ The remaining white space must form rectangular areas,
oriented either horizontally, vertically or diagonally.
- ➍ Two white rectangles must not be