proposition: Lemma C_dist_sym : forall a b, C_dist a b = C_dist b a.
proof: Proof. intros ; unfold C_dist ; rewrite Cnorm_minus_sym ; reflexivity. Qed.
imports: Rlimit Cbase Ctacfield Cnorm Cprop_base Rsequence_def Csequence Csequence_facts Cfunctions