Definition Concyclic_gen A B C D :=
  Concyclic A B C D \/ (Col A B C /\ Col A B D /\ Col A C D /\ Col B C D).Definition concy : arity Tpoint 4 := Concyclic_gen.

Lemma concy_perm_2 : forall (A B : Tpoint) (X : cartesianPower Tpoint 2), app_2_n concy A B X -> app_2_n concy B A X.