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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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Require Export area_elimination_lemmas.
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(** Length ratios eliminations *)
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(* Specifications: *)
Theorem non_zero_denom_on_line_d_1_length_ratio :
forall (Y P Q : Point) (l : F), on_line_d Y P Q l -> P<>Q.