Prof. Claudio Gorodski (Universidade de São Paulo) war zu einem vierwöchigen Forschungsaufenthalt am Institut für Geometrie und Topologie zu Besuch und sprach am 26.Juli 2022 im Oberseminar zum Thema "A diameter gap for isometric quotients of the unit sphere".
Während seines Forschungsaufenthalts gab Prof. Gorodski eine Lecture Series zum Thema "Topics in Polar Actions":
Part 1: Polar actions
Part 2: Orbifold points
Part 3: Variationally complete actions
Abstract:
Part 1 introduces polar actions and culminates with Heintze, Liu and Olmos’s argument to characterize them in terms of integrability of the distribution of normal spaces to the principal orbits. The other two lectures are devoted to two of Lytchak and Thorbergsson’s results. In Part 2 we briefly review Riemannian orbifolds from the metric point of view, andexplain their characterization of orbifold points in the orbit space of a proper and isometric action in terms of polarity of the slice representation above. In Part 3 we present their proof of the fact that variationally complete actions in the sense of Bott and Samelson are hyperpolar.
