Event time:

Thursday, February 1, 2007 - 11:30am to Wednesday, January 31, 2007 - 7:00pm

Location:

431 DL

Speaker:

Jesse Johnson

Speaker affiliation:

Yale

Event description:

The mapping class group of a Heegaard splitting is the group

of automorphisms of the ambient manifold that take the Heegaard surface

onto itself. There is a canonical homomorphism from this group into the

mapping class group of the 3-manifold. I will outline a proof that for

high distance Heegaard splittings this homomorphism is an isomorphism,

then describe examples of low distance, irreducible Heegaard for which

the kernel is infinite.