fact: Axiom Lookup_undef: forall p cn msig , Lookup p cn msig = None <-> (forall cn' m, ~ lookup p cn msig (cn',m)).
imports: Coq(List) Coq(ListSet) Coq(FSetInterface) Coq(Bool) Coq(ZArith) Coq(Relation_Operators) JML(ListHelpers)