smallest algebra
posted by sxxx123456 .
Let F be a family of subsets of a set X such that empty set is the element of F. A subset A of X belongs to F1 if and only if either A is a subset of F or complement of A is the subset of F. A subset B of X belongs to F2 if and only if B is a finite intersection of sets in F1. A subset C of X belongs to F3 if and only if C is a finite union of sets in F2. Show that F3 is the smallest algebra which contains F.

Why not try and trick one of your other profs to do this for you?

becouse they couldn't help me :(