If P and Q are two sets, we shall define a new set P ∩Q, called the intersection of P and Q, as follows: P ∩ Q is the set which contains those and only those elements which belong to both P and Q. As an example, consider the logical possibilities listed in Figure . Let P be the subset in which candidate A wins at least three primaries, ., the set {P1, P2, P3, P4, P7, P13, P19}; let Q be the subset in which A wins the first two primaries, ., the set {P1, P2, P3, P4, P5, P6}. Then the intersection P ∩Q is.
