Eighty Fourth Meeting of the Transpennine Topology Triangle

University of Sheffield
Wednesday 11th July 2012 

Supported by the London Mathematical Society  


All talks will be in J11, the usual seminar room on J floor of the Hicks Building.
The morning and afternoon coffee/tea will be served in the I floor common room (I15) of the Hicks Building.
Lunch may be taken in any of several local venues and we expect to visit a nearby restaurant for early evening dinner.


11.00 11.30


Tea, Coffee and Biscuits

11.30 12.30


Philipp Wruck (Sheffield)

Uniqueness of equivariant Lefschetz numbers and some consequences

There are several notions of equivariant Lefschetz numbers in the literature. The main differences arise from basic properties of the action and the acting group, and whether one wants the Lefschetz number to be localized around fixed points or rather fixed orbits. I will discuss several approaches and give a sketch of proof that, after fixing some simple data via axioms, an equivariant Lefschetz number is unique. In the second part, I will give an outlook on topological equivariant intersection theory and how this can be used to give yet another description of a Lefschetz invariant which hopefully may be used for generalizations, e.g. to flows.

12.30 2.00


2.00 3.00


Peter Eccles (Manchester)

Self-intersection manifolds of immersions

Given a self-transverse immersion of a closed smooth manifold M of dimension n-k in a smooth manifold N of dimension n, the r-fold self-intersection set is the image of a closed manifold of dimension n-rk. A natural question is to ask which bordism classes of manifolds of dimension n-rk arise in this way for given N.  I will describe a general approach to this problem, illustrate it with some examples indicating in particular how it relates to some classical invariants in homotopy theory such as the Hopf invariant and Kervaire invariant.

3.00 4.00


Tea, Coffee and Biscuits

4.00 5.00


Andy Baker (Glasgow)

Calculations with commutative S-algebras

Commutative S-algebras are a modern incarnation of E-infinity ring spectra. I'll discuss some constructions and show how to do calculations with some examples using topological Andre-Quillen theory. I'll give the background necessary to follow this.

Everyone who wishes to participate is welcome, particularly postgraduate students. We shall operate the usual criteria for assistance with travel expenses. Beneficiaries will need to complete the standard forms (available from the main TTT page), and should come with NI numbers and details of UK bank accounts if they want to complete the form on the day. 

Escape routes

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