Hello!
Let (X,T) be a topological space. then int(B) = unification {U | U is a subset of B, U is in T}
But what's Int(B) in A? Written: int(B) with a lowercase A on the bottom right part of the word int. I don't understand the meaning of it.
Isnt int(B) in A the same as int(B)?

Thanks!
Tomer.