Section Length_4.
Context `{TnEQD:Tarski_neutral_dimensionless_with_decidable_point_equality}.
Notation "l1 =l= l2" := (EqL l1 l2) (at level 80, right associativity).

Lemma ex_eql : forall l1 l2, (exists A , exists B, Len A B l1 /\ Len A B l2)  -> l1 =l= l2.