Topology Seminar 2015--2016

Speaker: Diego Vela

Title: Intro to Heegaard Floer Homology part 2

Abstract: I this talk we give a brief introduction into Heegaard Floer Homology and introduce the d-invariant. If time we will see an application.

Date / Time: February 26th, 3pm

Location: Clearihue D125.


Speaker: Diego Vela

Title: Intro to Heegaard Floer Homology

Abstract: I this talk we give a brief introduction into Heegaard Floer Homology and introduce the d-invariant. If time we will see an application.

Date / Time: February 19th, 3pm

Location: Clearihue D125.

Speaker: Diego Vela (U.Vic)


Title: An introduction to (Heegaard-Floer) d-invariants

Abstract: In this talk we will introduce the d-invariants which arise from Haegaard Floer homology and discuss some examples.

Date / Time: February 5th, 3:30pm (half-hour late start)

Location: Clearihue D125.


Speaker: Courtney Thatcher (U.Puget Sound)

Title: Free group actions on SnxS

Abstract: The spherical space form problem - the classification of all groups that act freely on Sn - was first stated by Hopf in 1925, and in 1978, Madsen, Thomas, and Wall proved that a finite group G can act freely on a sphere if and only if for every prime p, every subgroup of order p2 and order 2p is cyclic. An extension of this question - what groups can act freely on SnxSn - has still not been answered completely. A group G that acts on SnxSn cannot contain A4 or ZpxZpxZp  with p>3 prime, as a subgroup, but it is not known whether ZpxZpx~SL2(F2) can act on SnxSn for example.

In this talk I will give some of the history of the topological spherical space form problem and the classification of lens spaces. Additionally, I will present what is known about how both Zp and ZpxZp can act on SnxSn, and what this says about ZpxZpx~SL2(F2).

Date / Time: January 22nd, 3pm. 

Location: Clearihue D125


Speaker: Robin Koytcheff (U.Mass. Amherst)

Title: Homotopy string links, configuration spaces, and the kappa invariant.

Abstract: A link is an embedding of disjoint circles in space.  A link homotopy is a path of links where distinct components may not pass through each other, but where a component may pass through itself.  In the 1990s, Koschorke conjectured that link homotopy classes of n-component links can be distinguished by the kappa invariant.  This invariant is essentially the map that they induce on configuration spaces of n points, and it can be thought of as an evaluation map.  In joint work with Cohen, Komendarczyk, and Shonkwiler, we recently proved an analogue of this conjecture for long links (a.k.a. string links).  A key ingredient is establishing a multiplication on maps of configuration spaces, akin to concatenation of loops in a space.  This work is related to recent joint work with Budney, Conant, and Sinha on finite-type knot invariants and the Goodwillie—Weiss “Taylor tower” for the space of knots.

Date / Time: January 15th, 3pm. 

Location: Clearihue D125


Speaker: Ryan Budney

Title: An operadic perspective on satellite operations

Abstract: This talk will describe how all the "basic" operations on knots, such as connect sum and satellite operations fit into a homotopy-theoretic perspective.  Not only do the operations come from the action of an operad, but this operad encodes the homotopy-type of the space of knots in S3.

Date / Time: Wednesday October 21st 2pm--3pm, in Elliott room 167.


Speaker: Diego Vela 

Title: Introduction to the n-solvable filtration, part II

Abstract: An introduction to the Cochrane-Orr-Teichner filtration of knot concordence. 

Date / Time: Wednesday September 30th. 2pm--3pm, in Elliott room 167.


Speaker: Diego Vela 

Title: Introduction to the n-solvable filtration

Abstract: An introduction to the Cochrane-Orr-Teichner filtration of knot concordence. 

Date / Time: Wednesday September 23rd. 2pm--3pm, in Elliott room 167.