Categories in Low-dimensional topology, from braids to surfaces embedded in 4-manifolds.

by Quentin Faes (UCLouvain)

Tuesday 14 Oct 2025, 14:00 → 15:20 Europe/Brussels

B/2nd floor-B.203 - Seminar room (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

Part 1 (50 min): In this first part I will explain how the search for topological invariants (of braids, knots, 3-manifolds...) naturally leads to the definition of some categories. This in turn creates a bridge between algebra/representation theory and topology. I will try to give an overview from dimension 2 to dimension 4.

Part 2 (30 min): (Joint work with A. Beliakova and M. de Renzi) In this second part, I will describe a categorical setting that yields invariants of ribbon surfaces in 4-dimensional handlebodies up to some deformations.