Print Friendly printer friendly
 Events
University of Manitoba
Wed 29 Mar 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
The spaces of left and circular orderings of a group
ESB 4133 (PIMS Lounge)
Wed 29 Mar 2017, 3:15pm-4:15pm

Abstract

A group is left-orderable if it has a strict total ordering that is invariant under multiplication from the left. For countable groups, this is equivalent to acting on the real line by order-preserving homeomorphisms. A group being circularly orderable has a slightly trickier algebraic definition than left-orderability, but in the countable case boils down, as expected, to the existence of a orientation-preserving action by homeomorphisms on the circle.

The set of all left-orderings of a group forms a topological space, and similarly, so does the set of all circular orderings.  I will provide an introduction to these spaces, and discuss recent progress towards understanding the structure of groups whose spaces of circular orderings are “degenerate”, in the sense that they consist simply of a finite set of points with the discrete topology. This is joint work with Cristobal Rivas and Kathryn Mann.
hide
McMaster University
Wed 5 Apr 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
Group actions on homology 3-spheres
ESB 4133 (PIMS Lounge)
Wed 5 Apr 2017, 3:15pm-4:15pm

Abstract

I will discuss finite group actions on integral or rational homology 3-spheres. The main examples for this talk are the Brieskorn integral homology 3-spheres M(p,q,r) arising from isolated singularities, which bound smooth 4-manifolds with definite intersection forms. In addition, there are special infinite families of Brieskorn homology 3-spheres which can be realized as boundaries of smooth contractible 4-manifolds. We ask whether the free periodic actions on Brieskorn spheres extend to smooth actions with isolated fixed points on one of these associated 4-manifolds.
hide
UBC
Wed 12 Apr 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
TBA
ESB 4133 (PIMS Lounge)
Wed 12 Apr 2017, 3:15pm-4:15pm

Abstract


hide
UBC
Wed 19 Apr 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
TBA
ESB 4133 (PIMS Lounge)
Wed 19 Apr 2017, 3:15pm-4:15pm

Abstract


hide
MIT
Wed 3 May 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
TBA
ESB 4133 (PIMS Lounge)
Wed 3 May 2017, 3:15pm-4:15pm

Abstract


hide
 
Top