proposition: Lemma path_toS_app beta t gamma : path_toS gamma t beta -> forall alpha s, path_toS beta s alpha -> path_toS gamma (s++t)%list alpha.
proof: Proof. induction 2. - cbn; right with beta; auto. - cbn; right with gamma0; auto. Qed.
imports: hydras(DecPreOrder Canon MoreLists First_toggle OrdNotations) Coq(Lia)