Day 2 (Wednesday 20 April) @ 11:30–13:00

Marcello Seri (University of Groningen)

A snapshot of sub-Riemannian Laplacians

The study of intrinsic Laplacians on sub-Riemannian manifolds is still relatively young.In this short presentation, we will introduce the concept and give brief panoramic of the current state of the theory, focusing the attention on some of the many interesting open questions.

Federica Pasquotto (Leiden University)

A differentiable and symplectic point of view on orbifolds

 In this talk I would like to discuss recent work with T. Rot which aims at extending basic notions and results in differential topology to the orbifold setting: in particular, the definition of degree of an orbifold map, and properties of the group of orbifold diffeomorphisms. 

I also hope to describe how these questions have natural connections with (and extension to) the realm  of symplectic topology, where orbifolds naturally arise in the context of symplectic reduction.

Magdalena Kedziorek (Radboud University)

Uniqueness of rational equivariant K-theory

One of the recent themes in algebraic topology concentrates on the different levels of commutative multiplicative structures present in equivariant homotopy theory, i.e. the homotopy theory which takes symmetries given by a group G into account.

I will start this talk by explaining why we should expect different levels of commutativity in equivariant homotopy theory. Working rationally and with a finite group G, one can simplify topological complexity of equivariant stable homotopy theory and produce a purely algebraic model for it. Using this algebraic description, I will discuss a recent result stating that for a finite abelian group G, rational G-equivariant K-theory is unique when considered with the highest level of commutative multiplication.

This is joint work with A.M. Bohmann, C.Hazel, J.Ishak and C.May.