Require Export GeoCoq.Tarski_dev.Ch04_col.
Section Equivalence_between_decidability_properties_of_basic_relations.
Context `{Tn:Tarski_neutral_dimensionless}.

Lemma eq_dec_implies_l4_2 :
(forall A B:Tpoint, A=B \/ A<>B) ->
forall A B C D A' B' C' D', IFSC A B C D A' B' C' D' -> Cong B D B' D'.