code: static public Probability xor(Probability probability1, Probability probability2) {
          double p1 = probability1.value;
          double p2 = probability2.value;
          return new Probability(p1 * (1.0d - p2) + p2 * (1.0d - p1));
      }
docs: This function returns the logical exclusive disjunction of the specified probabilities.  The value
  of the logical exclusive disjunction of two probabilities is sans(P, Q) + sans(Q, P).
  
  @param probability1 The first probability.
  @param probability2 The second probability.
  @return The logical exclusive disjunction of the two probabilities.