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

Lemma th12: forall A B C A' B' C', ~ ColH A B C -> ~ ColH A' B' C' -> CongH A B A' B' -> CongH A C A' C' -> CongaH B A C B' A' C' -> CongaH A B C A' B' C' /\ CongaH A C B A' C' B' /\ CongH B C B' C'.