Section e1_diese_def.
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.

Lemma E_tau_cone_law : Cone_law E_tau.