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(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008                                           *)
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Lemma l3_44: forall O A X P Q U R G r N,
on_line_d P O A r ->
inversion Q P O A ->
is_midpoint U P O ->
inter_lc R O X U N ->
inversion G R O A ->
perp G Q O A.