abelian category as balanced category
2. Proof
Suppose is a bimorphism. Then by monomorphism as kernel of the cokernel and cokernel and epimorphism in an abelian category we conclude, that
is an equalizer
Thus using
we get a morphism such that
hence by monic split epi as isomorphism is an isomorphism
Alternatively:
direct consequence of the image coimage factorization
2.1. a)
Suppose is a bimorphism. By equalizer and equal maps it suffices to show, that is an equalizer of some map.
By regular monomorphism it follows that each monomorphism, hence also is an equalizer.