Section Quadrilateral.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.

Lemma midpoint_midpoint_col : forall A B A' B' M,
A <> B ->
Midpoint M A A' -> Midpoint M B B' ->
Col A B B' ->
A' <> B' /\ Col A A' B' /\ Col B A' B'.