Section Dimension.
Context `{Tn:Tarski_neutral_dimensionless}.

Lemma extension_to_3d__upper_dim_3 : forall {Tm: Tarski_neutral_dimensionless}
{Tm2 : Tarski_neutral_dimensionless_with_decidable_point_equality Tm}
{M : Tarski_3D Tm2}
(f : @Tpoint Tn -> @Tpoint Tm),
extension f ->
@upper_dim_3_axiom Tn.