fact: Definition reachable_by_through_set (g: Gph) (S : list V) (P : Ensemble V) : Ensemble V:= fun n => exists s, In s S /\ reachable_by g s P n.
imports: Coq.Logic.ProofIrrelevance Coq.micromega.Lia CertiGraph.lib.Coqlib CertiGraph.lib.EnumEnsembles CertiGraph.lib.List_ext CertiGraph.lib.EquivDec_ext CertiGraph.graph.graph_model Coq.Lists.List Coq.Lists.ListDec