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(* 02110-1301 USA                                                     *)
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(*          Projet Formel - Calculus of Inductive Constructions V5.10        *)
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(*									     *)
(*	                       Pullbacks                  		     *)
(*									     *)
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(*									     *)
(*                     A. SAIBI	  May 95                  		     *)
(*									     *)
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Require Export Limit.
Require Export PULB.
Require Export Pullbacks.
Set Implicit Arguments.
Unset Strict Implicit.
(* Pullbacks *)
Section Fpullback_limit_def.
Variables (C : Category) (G : Functor PULB C).
SubClass Fpullback1 := Limit G.
Variable l : Fpullback1.
Definition Fibred1_prod := Lim l.
Definition Fibred1_p : Fibred1_prod --> G P1 := Limiting_cone l P1.
Definition Fibred1_q : Fibred1_prod --> G P3 := Limiting_cone l P3.

Lemma Prf_pb1_law1 :
Pullback_law1 (FMor G F12) (FMor G F32) Fibred1_p Fibred1_q.