proposition: Lemma axAC s t : mprv (s :/\: t ---> t :/\: s).
proof: Proof. rule axS; last apply axAEl. rule axS; last apply axAEr. drop. exact: axAI. Qed.
imports: mathcomp(all_ssreflect) CompDecModal.libs(edone base fset induced_sym) Setoid Morphisms Relation_Definitions