Topology Seminar talks at Southampton

The talks are all happening at University of Southampton (in person), on Highfield Campus (SO17 1BJ). For the building and the room, see the individual postings. Email the organiser ( d (dot) kasprowski (at) soton.ac.uk ) if you have questions.

More Pure Maths talks at Southampton: we run Pure Maths Colloquia, Pure Lunchtime Seminar, and Pure Postgraduate Seminar (link soon).

Upcoming talks

• Mon 16 Feb 2026 14:00 (in B54 / 8033 (8B)): Devarshi Mukherjee (Oxford): Equivariant bivariant K-theory for bornological algebras
  unroll abstract

  We introduce equivariant bivariant K-theory for bornological algebras by taking a presentable refinement of the bivariant K-theory defined by Cuntz-Meyer-Rosenberg. An upshot of this refinement is that we may purely formally define a Bost-Connes assembly map via localisation in the sense of Meyer-Nest. Another feature built into the refinement is a large UCT-class; on this UCT-class, we show that the (equivariant) rationalised Chern-Connes character from (equivariant) KK-theory to (equivariant) local cyclic homology is an equivalence. This is joint work with Anupam Datta.

• Mon 2 Mar 2026 14:00 (in B54 / 8033 (8B)): Mark Hagen (Bristol): TBA
  No abstract yet.
• Mon 9 Mar 2026 14:00 (in B54 / 8033 (8B)): Ulrich Bunke (Regensburg): TBA
  No abstract yet.
• Mon 16 Mar 2026 14:00 (in B54 / 8033 (8B)): Daniel Marlowe (Warwick): TBA
  No abstract yet.

Recent talks

• Mon 9 Feb 2026 14:00: Kamen Pavlov (Southampton): 4-manifolds with fundamental group a semidirect product of Z and Z/p
  unroll abstract

  The quadratic 2-type is a collection of invariants which plays a big role in the homotopy classification of 4-manifolds. I will recall a result from my talk last year that, for manifolds with fundamental group ZxZ/p, there are at most p many different homotopy types with fixed quadratic 2-type. I will explain how this has been improved to a complete classification by including an additional Z/p-valued intersection form, and also generalized to semidirect products of Z and Z/p.

• Tue 9 Dec 2025 14:00: Samik Basu (ISI Kolkata): The higher structure of unstable homotopy groups
  unroll abstract

  I will describe how the homotopy groups of spheres may be generated using suspensions, Whitehead products, and higher order operations, starting from the identity map, and the inclusion of wedge summands. This may be viewed as an unstable analogue of a theorem of Joel Cohen. This is joint work with David Blanc and Debasis Sen.

• Mon 8 Dec 2025 14:00: Sebastian Chenery (Bristol): Pullbacks of Sphere Fibrations over Connected Sums
  unroll abstract

  In this talk we will investigate pullback fibrations that arise when taken over connected sums. In particular, when the fibre is an odd-dimensional sphere, we will discuss some conditions under which the total space itself has the homotopy type of a connected sum with a gyration. This is joint work with Stephen Theriault.

• Mon 24 Nov 2025 14:00: Nansen Petrosyan (Southampton): Simple groups with strong fixed-point properties
  unroll abstract

  I will discuss a construction of finitely generated torsion-free groups for which any action on any finite-dimensional CW-complex with finite Betti numbers has a global fixed point.

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