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

Lemma congH_perms : forall A B C D, A<>B -> C<>D -> CongH A B C D -> (CongH B A C D /\ CongH A B D C /\ CongH C D A B /\ CongH D C A B /\ CongH C D B A /\ CongH D C B A /\ CongH B A D C).