Global Instance IncidLP_morphisml : Proper(EqL ==> eq ==> iff) IncidLP.Global Instance IncidLP_morphismr : Proper(eq ==> EqP ==> iff) IncidLP.

Lemma isosceles_congaH : forall A B C, ~ColH A B C -> CongH A B A C -> CongaH A B C A C B.