proposition: Lemma strictly_increasing_in_opp : forall D f, strictly_increasing_in D f -> strictly_decreasing_in D (-f)%F.
proof: Proof. intros D f Hf x y Dx Dy Hxy ; unfold opp_fct ; apply Ropp_lt_contravar, Hf ; assumption. Qed.
imports: Rbase Ranalysis Rinterval Rfunctions Rfunction_def Rfunction_facts Ranalysis_def Ranalysis_def_simpl MyRIneq MyR_dist Lra