Uniqueness theorem for completely non-degenerate B-groups

We prove that a completely non-degenerate B-group is uniquely determined by its factor: two such groups with conformally equivalent factors are Mobius conjugate. A similar property is inherent to the quasi-Fuchsian groups but not to degenerate B-groups. We also study the factor of a B-group as a triple: the main factor, the marked characteristic complex, and a homotopy class of maps of the rst to the second one.