A square of side 1 is divided into "a" strips by "a-1" equally spaced
red lines parallel to a side, and into "b" strips by "b-1" equally spaced
blue lines parallel to the red lines. Suppose that a does not divide b
and that b does not divide a. What is the smallest possible distance
between a red line and a blue line?
Edit: Actually, I think case one may be that assume (a,b) =/= 1. In that case since a does not divide b and b does not divide a, there must be at least one c such that (a,b) = c. In this case the red and blue lines most coincide, and so the minimum distance is 0. What about the case when (a,b) = 1?