proposition: Lemma ex_C_RInt_segm_minus (f g : C -> C) (z1 z2 : C) : ex_C_RInt_segm f z1 z2 -> ex_C_RInt_segm g z1 z2 -> ex_C_RInt_segm (fun z => f z - g z) z1 z2.
proof: Proof. intros. apply ex_C_RInt_segm_plus => //. by apply ex_C_RInt_segm_opp. Qed.
imports: Coq(Reals ssreflect) Coquelicot(Coquelicot)