proposition: Lemma par_assoc : ∀ p1 p2 p3, par p1 (par p2 p3) = par (par p1 p2) p3.
proof: Proof. intros p1 p2 p3. unfold par. rewrite unionmA. reflexivity. Qed.
imports: Coq(Utf8) Relational(OrderEnrichedCategory OrderEnrichedRelativeMonadExamples) mathcomp(ssreflect eqtype choice seq ssrfun ssrbool ssrnat) extructures(ord fset fmap) Mon(SPropBase) Crypt(Prelude Axioms ChoiceAsOrd StateTransformingLaxMorph choice_type pkg_core_definition RulesStateProb) Equations(Equations)