Section T8_4.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma per_cong : forall A B P R X ,
A <> B -> A <> P ->
Per B A P -> Per A B R ->
Cong A P B R -> Col A B X -> Bet P X R ->
Cong A R P B.