Matthias Schötz (ULB) will speak in the geometry seminar on Tuesday 15 January, at 1.30pm in the Salle de Profs. Matthias’ title is *Singular points in non-formal deformation quantization* and his abstract is below.

With this talk I try to give an overview of my past work during my phd and of some ideas that I would like to pursue the next years here in Brussels: When one examines the conditions under which formal power series in ħ, that occur in formal deformation quantization, actually converge, it is not unusual to find a holomorphic dependence on ħ with poles at certain values of ħ that accumulate at ħ=0. This behaviour seems to be not completely understood: From some perspectives this is just a nuisance, but sometimes it also is a key feature in the construction of non-formal deformation quantizations. I will try to explain what I know about this phenomenon (which gives me an excuse to give an introduction to formal and non-formal deformation quantization as well as (quantum-) phase space reduction) and why this might hint to some interesting mathematics waiting to be explored (which might require some operator algebra).