proposition: Lemma swap_abs : forall E Pt A B (Mb: decl A E |- Pt := B) (pos: Pos (buildT Mb)) (N: PlaceHolder (PAbs pos)), isAbs (swap N).
proof: Proof. intros E Pt A B Mb pos N. eapply abs_isAbs; rewrite swap_term_is; simpl; eauto. Qed.
imports: CoLoR(RelExtras ListExtras TermsBuilding)