fact: Definition Dag (g: Graph) := forall x, not_in_circle g x.
imports: Coq.Logic.ProofIrrelevance Coq.Sets.Ensembles Coq.Sets.Finite_sets 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.subgraph2