Require Export B9_Inegalite_Triang.
Section METRIC_BASICS.
Definition LS0 := Distance Oo Oo.

Lemma HalfLineAntisymLSlt  : forall A B C : Point,
A <> B ->
HalfLine A B C ->
LSlt (Distance A B) (Distance A C) ->
~LSlt (Distance A C) (Distance A B).