proposition: Lemma weak_edge_prop_Disjoint: forall (P1 P2: V -> Prop) (g: PreGraph V E), Disjoint _ P1 P2 -> Disjoint _ (weak_edge_prop P1 g) (weak_edge_prop P2 g).
proof: Proof. intros. unfold weak_edge_prop. rewrite Disjoint_spec in *. firstorder. Qed.
imports: Coq.Logic.ProofIrrelevance Coq.Sets.Ensembles Coq.Sets.Finite_sets Coq.Classes.Morphisms CertiGraph.lib.Coqlib CertiGraph.lib.Ensembles_ext CertiGraph.lib.relation_list CertiGraph.lib.List_ext CertiGraph.lib.Equivalence_ext CertiGraph.lib.EquivDec_ext VST.msl.Coqlib2 Coq.Lists.List CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.reachable_ind