(* Lemma test_on_line_d_13 : forall Y P Q A C D lambda, on_line_d Y P Q lambda ->  Y<>A -> parallel C D Y A -> False -> C**D/Y**A = C**D. *)
(** Test inter_ll in a ratio *)
(** Test cases where Y occurs both in denominator and numerator *)

Lemma test_inter_ll_5 :  forall Y P Q U V A C,
inter_ll Y P Q U V ->  C<>Y -> parallel A Y C Y ->
A**Y/C**Y = A**Y/C**Y.