22 oct 2025 -- 14:00   [open in google calendar]

Centro de Giorgi, Sala Conferenze

Nicola Gigli will hold a double seminar: the first hour will be more basic and accessible to everyone, and the second hour will be more specialized.

Abstract.

The concepts of Sobolev functions, elliptic operators and Banach spaces are central in modern geometric analysis. In the setting of Lorentzian geometry, however, unless one restricts the attention to Cauchy hypersurfaces these do not have a clear analogue, due to the signature of the metric tensor. Aim of the talk is to discuss some recent observations in this direction centered around the fact that for $p<1$ the $p$-D’Alambertian is elliptic on the space of time functions.

The talk is mostly based on joint project with Beran, Braun, Calisti, McCann, Ohanyan, Rott, Saemann.

In the second part of the talk I will dig down into the concept of `hyperbolic Banach space’, extracted from an upcoming work of mine.