proposition: Lemma subst_var_a s': σ p q • s' = A -> s' = A.
proof: Proof. intros H4. destruct s'; try discriminate. cbn in H4. destruct f as [|[|[]]]; cbn in H4; try discriminate; auto. Qed.
imports: List Lia Program.Program Undecidability.HOU(std.std axioms) RelationClasses Morphisms Init.Wf Init.Nat Setoid Undecidability.HOU(calculus.calculus second_order.goldfarb.encoding) FinFun Coq.Arith.Wf_nat