Kinesys lands on Polygon in the middle of a field farmed on a grid, where every plant grows exactly on an intersection. Nine glowing lanterns mark the intersections of a square: it’s the most famous challenge on the planet, and whoever solves it wins a free ride on the octahedral Ferris wheel.
The rules are simple: four straight lines, without ever lifting the pen. Liz tries three times and fails three times. Dord tries once and declares the problem “ill-posed.” M00N floats thoughtfully above the field, then drifts quite a long way from the square. “Maybe you have to look at it from farther away!”
The Riddle
The dots in the figure are arranged on a square grid: the eight outer dots lie on the perimeter of a square, and the remaining one sits at its center.
The challenge is to cover all nine dots with four straight line segments, without ever lifting your pen from the paper.
Hint
Read the rules again carefully: nobody said the segments have to stop at the dots or stay inside the square.
Solution
Here is the solution; of course there are others, symmetrical to this one.
What trips most people up is the assumption that they must cover the dots without leaving the square. In fact, the segments can (and must) extend beyond the outer dots: it’s no accident that this puzzle is often cited as the classic example of “thinking outside the box.” M00N was right.