Section Clos_Refl_Sym_Trans.
(** Reflexive-transitive closure is included in the reflexive-symmetric-transitive closure *)
(** Reflexive closure is included in the reflexive-transitive closure *)
(** Correctness of the reflexive-symmetric-transitive closure *)
(** Idempotency of the reflexive-symmetric-transitive closure operator *)

Lemma clos_rst_idempotent :
inclusion (clos_refl_sym_trans (clos_refl_sym_trans R))
(clos_refl_sym_trans R).