(***************************************************************************)
(* Formalization of the Chou, Gao and Zhang's decision procedure.          *)
(* Julien Narboux (Julien@narboux.fr)                                      *)
(* LIX/INRIA FUTURS 2004-2006                                              *)
(* University of Strasbourg 2008                                           *)
(***************************************************************************)

Lemma l3_43 : forall O A B X Y C D P Q R T r,
mratio C A B r ->
mratio D A B (0-r) ->
inter_ll P O A X Y ->
inter_ll Q O B X Y ->
inter_ll R O C X Y ->
inter_ll T O D X Y ->
parallel P R R Q ->
R<>Q ->
parallel T P T Q ->
T<>Q ->
P<>T ->
P<>R ->
~ Col P X Y ->
harmonic P Q R T.