Section Beeson_1.
(** Another proof of l2_11 without eq_dec_points but using Cong stability inspired by Micheal Beeson. #<a href="http://www.michaelbeeson.com/research/papers/AxiomatizingConstructiveGeometry.pdf"></a> # *)
Context `{Tn:Tarski_neutral_dimensionless}.
Variable Cong_stability : forall A B C D, ~ ~ Cong A B C D -> Cong A B C D.

Lemma l2_11_b : forall A B C A' B' C',
Bet A B C -> Bet A' B' C' -> Cong A B A' B' -> Cong B C B' C' -> Cong A C A' C'.