1. [10pt] Prove that for any sets ACU, and BCU where U is the universe, we have B - (A B) = B %3D Reminder (See Wikipedia for more information): Universe or Universal Set: Universe is the set of all elements in the context that is used for defining sets. All sets are considered to be subset of some large universal set. X is the Complement operator for X. X is defined as X = {r| x U and a X} X - Y is the Set Difference operator for X,Y. X - Y is defined as X -Y = {r U | r X and r Y} or equivalently X - Y = XnY