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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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unfold on_line_d in |- *.
intuition.
Qed.
unfold on_line_d in |- *.
intuition.
Qed.
unfold on_line in |- *.
intuition.
Qed.

Theorem non_zero_denom_on_line_1_length_ratio_seg :
forall (Y P Q : Point), on_line Y P Q -> P**Q <> 0.