# Father-son mathematicians fold math into fonts

## MIT’s Erik and Martin Demaine create puzzle typefaces to test new ideas

Dominick Reuter

A mathematician once posed a deceptively simple question. Can a single 2-D conveyor belt be stretched around a set of wheels such that the belt is taut and touches every wheel without crossing itself?

MIT computer scientist Erik Demaine pondered the problem. For just a few wheels, the solution is easy: Arrange four into a square, wrap the belt around the outside, and the problem is solved — one version of it, at least.

“The question is whether it’s always possible to solve no matter how you draw the wheels,” Demaine says. A complete solution would lay out a set of rules that applies to every possible wheel arrangement and number. “But so far every algorithm we’ve come up with has been foiled.”

One day Demaine was working on the problem with his dad, who happens to be an artist and mathematician, and a colleague. The trio got stuck. So they decided to take a break with another