Event time:

Tuesday, April 20, 2010 - 12:30pm to Monday, April 19, 2010 - 8:00pm

Location:

215 LOM

Speaker:

Tam Nguyen Phan

Speaker affiliation:

University of Chicago

Event description:

Cusp-decomposable manifolds form a large class of manifolds that

are not locally homogeneous and generally do not admit a nonpositively

curved metric, but smooth rigidity holds within this class of manifolds. I

will define cusp-decomposable manifolds and prove that they are smoothly

rigid within this class. I will also prove that the group of outer

automorphisms of the fundamental group of such manifolds is an extension

of an abelian group by a finite group. Elements of the abelian group are

induced by diffeomorphisms that are analogous to Dehn twists in surface

topology. This gives a simple description of self-diffeomorphisms of

cusp-decomposable manifolds up to homotopy.