Section weak_inverse_projection_postulate_weak_tarski_s_parallel_postulate.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
(** Formalization of a proof from Bachmann's article "Zur Parallelenfrage" *)

(* Specifications: *)
Lemma weak_inverse_projection_postulate__weak_tarski_s_parallel_postulate_aux :
forall A B C P T,
Per A B C -> InAngle T A B C ->
CongA P B A P B C -> Per B P T -> Coplanar A B C P ->
InAngle P A B C.
Lemma weak_inverse_projection_postulate__weak_tarski_s_parallel_postulate :
weak_inverse_projection_postulate -> weak_tarski_s_parallel_postulate.