End T4_2.
Hint Resolve not_col_permutation_1 not_col_permutation_2
not_col_permutation_3 not_col_permutation_4 not_col_permutation_5 : col.
Section T4_3.
Context `{Tn:Tarski_neutral_dimensionless}.

(** This lemma is used by tactics for trying several permutations. *)
Lemma Col_cases :
forall A B C,
Col A B C \/ Col A C B \/ Col B A C \/
Col B C A \/ Col C A B \/ Col C B A ->
Col A B C.