proposition: Lemma pr_and A B mu : \P_[mu] [predI A & B] = \P_[mu] A + \P_[mu] B - \P_[mu] [predU A & B].
proof: Proof. by rewrite pr_or opprB addrCA subrr addr0. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp classical_sets mathcomp_extra) xfinmap ereal reals discrete topology realseq realsum