proposition: Lemma eq_dec_cong_dec : (forall A B:Tpoint, A=B \/ A<>B) -> (forall A B C D, Cong A B C D \/ ~ Cong A B C D).
proof: Proof. intro eq_dec. apply (@cong_dec Tn (Build_Tarski_neutral_dimensionless_with_decidable_point_equality Tn eq_dec)). Qed.
imports: GeoCoq.Tarski_dev.Ch05_bet_le GeoCoq.Utils.all_equiv