proposition: Lemma plus_le_kleene a : a^+ <= a^*.
proof: Proof. by rewrite le_def kleeneSr addrCA adddd. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype choice order) mathcomp(fintype ssrnat bigop ssralg boolp classical_sets) dioid complete_lattice