Joint Colloquium: Tillmann -- What is the Thurston norm?

Note New Lunch Time: We shall be taking the speakers of the joint colloquium and the PDE
seminar to lunch, departing from the outside foyer, level 2 Carslaw at 12:30 p.m.  

 Stephan Tillmann (University of Melbourne) 

Title: What is the Thurston norm? 

Abstract: In the late seventies, Bill Thurston defined a semi-norm on the homology of a
3-dimensional manifold which lends itself to the study of manifolds which fibre over the
circle.  This led him to formulate the Virtual Fibration Conjecture, which is fairly
inscrutable and implies almost all major results and conjectures in the field.
Nevertheless, Thurston gave the conjecture "a definite chance for a positive answer" and
much research is currently devoted to it.  I will describe the Thurston norm, its main
properties and applications, as well as its relationship to McMullen’s Alexander norm
and the geometric invariant for groups due to Bieri, Neumann and Strebel.