(** To be equivalent is an equivalence relation *)
Section Equiv.
Context {T : Type} {K : AbsRing} {V : NormedModule K}.

Lemma equiv_trans :
forall {F : (T -> Prop) -> Prop} {FF : Filter F} (f g h : T -> V),
is_equiv F f g -> is_equiv F g h -> is_equiv F f h.