Spaces of Incompressible Surfaces

This is a "software upgrade" to a paper originally published in 1976, with cleaner statements and improved proofs. The main result is that, in a Haken 3-manifold, the space of all incompressible surfaces in a single isotopy class is contractible, except when the surface is the fiber of a surface bundle structure, in which case the space of all surfaces isotopic to the fiber has the homotopy type of a circle (the fibers). The main application from the 1976 paper is also rederived, the theorem (proved independently by Ivanov) that the diffeomorphism group of a Haken 3-manifold has contractible components, except in the case of certain Seifert manifolds when the components of the diffeomorphism group have the homotopy type of a circle or torus acting on the manifold.