(* construire a` partir de h, un cone r -> fpa *)
(* C'est la` ou` on a besoin que I ne soit pas vide *)
Variables (r : C) (h : r --> a).
Hypothesis p : Equalizer_eq k h.
Definition E_tau (x : PA k) :=
match x as x' return (Carrier (r --> FPA x')) with
| PA1 => h
| PA2 => h o k (Witness l)
end.

(* Specifications: *)
Lemma E_tau_cone_law : Cone_law E_tau.
Definition E_NT := Build_Cone E_tau_cone_law.