Imbeddings Of Three-manifold Groups (memoirs Of The American Mathematical Society)

This work deals with the two broad questions of how three-manifold groups imbed in one another and how such imbeddings relate to any corresponding $\pi _1$-injective maps. The focus is on when a given three-manifold covers another given manifold. In particular, the authors are concerned with 1) determining which three-manifold groups are not cohopfian—that is, which three-manifold groups imbed properly in themselves; 2) finding the knot subgroups of a knot group; and 3) investigating when surgery on a knot $K$ yields lens (or ''lens-like'') spaces and how this relates to the knot subgroup structure of $\pi _1(S^3-K)$. The authors use the formulation of a deformation theorem for $\pi _1$-injective maps between certain kinds of Haken manifolds and develop some algebraic tools. This paper deals with the two broad questions of how 3-manifold groups imbed in one another and how such imbeddings relate to any corresponding [lowercase Greek]Pi1-injective maps. In particular, we are interested in 1) determining which 3-manifold groups are no cohopfian, that is, which 3-manifold groups imbed properly in themselves, 2) determining the knot subgroups of a knot group, and 3) determining when surgery on a knot [italic]K yields a lens (or "lens-like") space and the relationship of such a surgery to the knot-subgroup structure of [lowercase Greek]Pi1([italic]S3 - [italic]K). Our work requires the formulation of a deformation theorem for [lowercase Greek]Pi1-injective maps between certain kinds of Haken manifolds and the development of some algebraic tools