proposition: Lemma eq_in_pr A B mu : {in dinsupp mu, A =i B} -> \P_[mu] A = \P_[mu] B.
proof: Proof. move=> eq_AB; apply/eq_psum => x; case/boolP: (x \in dinsupp mu). by move/eq_AB; rewrite -!topredE => /= ->. by move/dinsuppPn=> ->; rewrite !mulr0. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp classical_sets mathcomp_extra) xfinmap ereal reals discrete topology realseq realsum