Tue, 11 Jun 2024
16:00 - 17:00
Florent Baudier

A central theme in the 40-year-old Ribe program is the quest for metric invariants that characterize local properties of Banach spaces. These invariants are usually closely related to the geometry of certain sequences of finite graphs (Hamming cubes, binary trees, diamond graphs...) and provide quantitative bounds on the bi-Lipschitz distortion of those graphs.

A more recent program, deeply influenced by the late Nigel Kalton, has a similar goal but for asymptotic properties instead. In this talk, we will motivate the (asymptotic) notions of infrasup umbel convexity (introduced in collaboration with Chris Gartland (UC San Diego)) and bicone convexity. These asymptotic notions are inspired by the profound work of Lee, Mendel, Naor, and Peres on the (local) notion of Markov convexity and of Eskenazis, Mendel, and Naor on the (local) notion of diamond convexity. 

All these metric invariants share the common feature of being derived from point-configuration inequalities which generalize curvature inequalities.

If time permits we will discuss the values of these invariants for Heisenberg groups.

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