Dr. Cynthia Hog-Angeloni (Frankfurt)
28/2/02, ore 15:00, Sala dei Seminari

  	     "A uniqueness theorem for regular 
	neighborhoods of 2-complexes in 3-manifolds"

(joint with Janina Glock)

Abstract:  Every compact connected orientable PL 3-manifold
collapses to a 2-dimensional spine. Conversely, starting with a
2-complex K^2, the questions of existence and uniqueness of
3-manifold-thickenings arise. We begin with an overview of
existence results. We then describe - and illustrate with examples
- four typical obstacles to uniqueness, from which we collect
assumptions for our uniqueness theorem, which we are going to
state and explain.  It generalizes results of D. Repovs & al.