proposition: Lemma psum_coupling_left : psum d = psum c1.
proof: Proof. rewrite (@psum_pair R A1 A2 d). f_equal. destruct hCoupl as [lH rH]. rewrite -lH. unfold lmg. apply boolp.funext. intro x1. rewrite dfstE. reflexivity. destruct d as [dd d2 d3 d4]. simpl. assumption. Qed.
imports: Mon(FiniteProbabilities SPropMonadicStructures SpecificationMonads MonadExamples SPropBase FiniteProbabilities) Coq(RelationClasses Morphisms) Relational(OrderEnrichedCategory OrderEnrichedRelativeMonadExamples Commutativity) mathcomp(all_ssreflect all_algebra reals distr realsum) Crypt(Axioms ChoiceAsOrd only_prob.SubDistr)