A set is any collection of objects. A proper subset of a set Is Itself a subset of the set, but not vice versa. The empty set Is a subset of every set. If A u = 0 , then A= 0 and B= 0 . If A n B = 0 ,...

A set is any collection of objects. A proper subset of a set Is Itself a subset of the set, but not vice versa. The empty set Is a subset of every set. If A u = 0 , then A= 0 and B= 0 . If A n B = 0 , then A = 0 or B = 0 or both A and B are empty sets. (A u Arc = 0 . [An (Bu C)j(' = (A n By n (A n c)c n(A) + '(B) = n(A u B) + n(A n B) If A B, then n(B) = n(A) + 11 13). The number of permutations of n distinct objects taken all together is n! F(n, r) = r).