(** Definitions of some environments **)
Definition empty_genv cenv := Build_genv (Globalenvs.Genv.empty_genv fundef type nil) cenv.Definition empty_tenv := PTree.empty val.Definition empty_environ cenv : environ :=
mkEnviron (filter_genv (empty_genv cenv)) (Map.empty _) (Map.empty _).

Lemma Z2R_pow_0_lt: forall e, 0 <= e -> Rdefinitions.Rlt 0 (Fcore_Raux.Z2R (2 ^ e)).