Hint Resolve col_par_1 col_par_2 col_par_3 col_par_4 : Geom.

(* Specifications: *)
Lemma par_col_col_1 : forall A B C D,
parallel A B C D ->
Col A B C ->
Col A B D.
Lemma par_col_col_2 : forall A B C D,
parallel A B C D ->
Col A B D ->
Col A B C.
Lemma par_col_col_3 : forall A B C D,
parallel A B C D ->
Col A C D ->
Col B C D.