fact: Definition mark1 (m1 : NodePred V) (n : V) (m2 : NodePred V) : Prop := vvalid g n /\ m2 n /\ forall n', n <> n' -> (m1 n' <-> m2 n').
imports: Coq.Logic.ProofIrrelevance CertiGraph.lib.Ensembles_ext Coq.Lists.List Coq.Classes.Morphisms CertiGraph.lib.Coqlib CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext VST.msl.Coqlib2 CertiGraph.graph.graph_model CertiGraph.graph.path_lemmas CertiGraph.graph.reachable_computable CertiGraph.graph.reachable_ind CertiGraph.graph.graph_gen CertiGraph.graph.graph_relation CertiGraph.graph.subgraph2