Deltas between Sets Measured in Time

In continuous hierarchy, set subtraction computes a delta between sets. We don't yet know if this result is a set or not. For example, if you have a set A, and the subtraction operator -, the A - A is not the empty set. Each time you measure A, you get a different result, so the two references to A are references to different sets in time. So you might look at the equations A(t1) - A(t2) = {}(t2 - t1) As t1 approaches t2, A - A becomes the empty set.