I've just stumbled upon this notation in a text about optimalisation with no explanation as to what they mean (suggesting they are widely used and well known?). $A$ is a set (a convex set in this case) and the notation I am not sure of is: $$clo(A), int(A), rint(A)$$
I only need to know the names, as attempting to google these yielded no results. Thanks!
edit: I just found http://en.wikipedia.org/wiki/Interior_(topology) so that's probably one of them!