proposition: Lemma right_subst_eqs E sigma: right_side (sigma •₊₊ E) = sigma •₊ right_side E.
proof: Proof. unfold right_side; induction E as [| []]; cbn; congruence. Qed.
imports: List Lia Undecidability.HOU(std.std calculus.calculus unification.higher_order_unification)