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

Theorem th6_41 : forall A B C M N L P K:Point,
is_midpoint M A B ->
is_midpoint N A C ->
is_midpoint K B C ->
is_midpoint L A K ->
on_inter_parallel_parallel P A C M K B N ->
B<>C ->
P<>L ->
P<>A ->
P<>K ->
parallel L P B C ->
S A B C <> 0 ->
2+2 <> 0 ->
L**P / B**C = (1+2)/(2+2).