How do you do this puzzle?

Question

ok think of a perfect square with an X in the middle touching each inside corner and then on the outside there is a half circle connected to each side so you should have four half circles, so draw that, now you have to draw that without going over the same line and you cant lift your pen/pencil. ok does anyone know how to do this!?! its driving me insane

Answer 1

it is a one-stroke problem.

When a vortex have odd-number of segments connect to it,

it should be either the starting or ending point of the one-stroke solution.

This shape has 4 such vortices,  so it can't be solved the normal way. Maybe there is a tricky way?

A trick for this: maybe fold the paper to the pen, so it could beam (move)  to other location without being lifted. (extra dimension?)

Answer 2

That particular problem is impossible because according to the mathematician Leonard Euler, you won't be able to visit each edge once to draw that figure because more than 2 vertices have an odd number of edges connecting to it.

It is explains it all here:

http://en.wikipedia.org/wiki/Eulerian_pa...

I know that it is wikipedia but I had a math teacher explain it to me and he gave the same information as on the page.