Ltac Circle := auto with circle.Ltac treat_equalities :=
try treat_equalities_aux;
repeat
  match goal with
   | H:(Cong ?X3 ?X3 ?X1 ?X2) |- _ =>
      apply cong_symmetry in H; apply cong_identity in H;
      smart_subst X2;clean_reap_hyps
   | H:(Cong ?X1 ?X2 ?X3 ?X3) |- _ =>
      apply cong_identity in H;smart_subst X2;clean_reap_hyps
   | H:(Bet ?X1 ?X2 ?X1) |- _ =>
      apply  between_identity in H;smart_subst X2;clean_reap_hyps
   | H:(Midpoint ?X ?Y ?Y) |- _ => apply l7_3 in H; smart_subst Y;clean_reap_hyps
   | H : Bet ?A ?B ?C, H2 : Bet ?B ?A ?C |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T : A=B) by (apply (between_equality A B C); finish);
                       smart_subst A;clean_reap_hyps
   | H : Bet ?A ?B ?C, H2 : Bet ?A ?C ?B |- _ =>
     let T := fresh in not_exist_hyp (B=C); assert (T : B=C) by (apply (between_equality_2 A B C); finish);
                       smart_subst B;clean_reap_hyps
   | H : Bet ?A ?B ?C, H2 : Bet ?C ?A ?B |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T : A=B) by (apply (between_equality A B C); finish);
                       smart_subst A;clean_reap_hyps
   | H : Bet ?A ?B ?C, H2 : Bet ?B ?C ?A |- _ =>
     let T := fresh in not_exist_hyp (B=C); assert (T : B=C) by (apply (between_equality_2 A B C); finish);
                       smart_subst A;clean_reap_hyps
   | H:(Le ?X1 ?X2 ?X3 ?X3) |- _ =>
      apply le_zero in H;smart_subst X2;clean_reap_hyps
   | H : Midpoint ?P ?A ?P1, H2 : Midpoint ?P ?A ?P2 |- _ =>
     let T := fresh in not_exist_hyp (P1=P2);
                      assert (T := symmetric_point_uniqueness A P P1 P2 H H2);
                      smart_subst P1;clean_reap_hyps
   | H : Midpoint ?A ?P ?X, H2 : Midpoint ?A ?Q ?X |- _ =>
     let T := fresh in not_exist_hyp (P=Q); assert (T := l7_9 P Q A X H H2);
                       smart_subst P;clean_reap_hyps
   | H : Midpoint ?A ?P ?X, H2 : Midpoint ?A ?X ?Q |- _ =>
     let T := fresh in not_exist_hyp (P=Q); assert (T := l7_9_bis P Q A X H H2);
                       smart_subst P;clean_reap_hyps
   | H : Midpoint ?M ?A ?A |- _ =>
     let T := fresh in not_exist_hyp (M=A); assert (T : l7_3 M A H);
                       smart_subst M;clean_reap_hyps
   | H : Midpoint ?A ?P ?P', H2 : Midpoint ?B ?P ?P' |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T := l7_17 P P' A B H H2);
                       smart_subst A;clean_reap_hyps
   | H : Midpoint ?A ?P ?P', H2 : Midpoint ?B ?P' ?P |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T := l7_17_bis P P' A B H H2);
                       smart_subst A;clean_reap_hyps
   | H : Midpoint ?A ?B ?A |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T := is_midpoint_id_2 A B H);
                       smart_subst A;clean_reap_hyps
   | H : Midpoint ?A ?A ?B |- _ =>
     let T := fresh in not_exist_hyp (A=B); assert (T := is_midpoint_id A B H);
                       smart_subst A;clean_reap_hyps
   | H : OnCircle ?A ?A ?B |- _ =>
      apply cong_reverse_identity in H;smart_subst B;clean_reap_hyps
   | H : OnCircle ?B ?A ?A |- _ =>
      apply cong_identity in H;smart_subst B;clean_reap_hyps
   | H : InCircle ?B ?A ?A |- _ =>
      apply le_zero in H;smart_subst B;clean_reap_hyps
   | H : OutCircle ?A ?A ?B |- _ =>
      apply le_zero in H;smart_subst B;clean_reap_hyps
end.

Lemma mid_chord__diam_or_ncol : forall O P A B T, A <> B -> OnCircle A O P -> OnCircle B O P -> Midpoint T A B -> Diam A B O P \/ ~Col O A T /\ ~Col O B T.