proposition: Lemma swap_right_app : forall E PtL PtR A B (Ml: E |- PtL := A --> B) (Mr: E |- PtR := A) (pos: Pos (buildT Mr)) (N: PlaceHolder (PAppR Ml pos)), isApp (swap N).
proof: Proof. intros E PtL PtR A B Ml Mr pos N. eapply app_isApp; rewrite swap_term_is; simpl; eauto. Qed.
imports: CoLoR(RelExtras ListExtras TermsBuilding)