proposition: Lemma axEUI2 s t : mprv (s ---> EX (EU s t) ---> EU s t).
proof: Proof. rewrite /EU. rewrite -> (axDNI s) at 1. Intro. ApplyH ax_contraNN; Intro. Suff (AX (AR (~~: s) (~~: t))). drop. apply: rNorm. exact: axDNI. ApplyH axARu. Qed.
imports: mathcomp(all_ssreflect) CompDecModal.libs(edone base fset induced_sym) Setoid Morphisms Relation_Definitions