Hint Resolve between_exchange2 outer_transitivity_between between_exchange4 : between.
Section T2_4.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma l3_9_4 : forall A1 A2 A3 A4, Bet_4 A1 A2 A3 A4 -> Bet_4 A4 A3 A2 A1.