You're lost in a forest of known shape. What's the shortest path guaranteed to escape?
You're dropped somewhere inside a forest whose exact shape and size you know, but you have no idea where in it you are or which way you're facing. What is the shortest walking path you could follow that's guaranteed to reach the forest's edge, no matter your hidden starting point or orientation?
Reveal the answer
For some shapes it's known. A circular forest? Walk a straight line the length of the diameter. An infinite strip? A specific V-shaped zigzag of lines and curves is optimal. But for most shapes, including something as simple as an equilateral triangle, the best escape path is still unknown. Richard Bellman posed the general problem in 1956, and it remains unsolved for the majority of shapes to this day.