proposition: Lemma le_hprop m n : forall e e' : m <= n, e = e'.
proof: Proof. induction e using le_dep. intros e'. DepElim.depelim e'. constructor. exfalso; now apply le_Sn_n in e'. intros. depelim e'. exfalso; clear IHe; now apply le_Sn_n in e. now rewrite (IHe e'). Qed.
imports: Program Equations.Prop.EqDecInstances Equations.Prop.Equations