Одељење за математику, 15. децембар 2023.

• 08. Децембар, 2023
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Наредни састанак Семинара биће одржан у петак, 15. децембра 2023, у сали 301ф Математичког института САНУ са почетком у 14.15. У питању је заједнички састанак са Логичким семинаром.

Предавач: Ilijas Farah, York University, Toronto
 
Наслов предавања: CORONA RIGIDITY
 
Апстракт: This talk will be about a story that started with Weyl’s work on compact perturbations of pseudodifferential operators. The Weyl-von Neumann theorem asserts that two self-adjoint operators on a complex Hilbert space are unitarily equivalent modulo the compacts if and only if their essential spectra coincide. Later on, this was extended to normal operators by Berg and Sikonia. New impetus to this study was given in the work of Brown, Douglas, and Fillmore, who replaced single operators with (separable) C*-algebras and compact perturbations with extensions by K(H). After passing to the quotient (the Calkin algebra, Q) and identifies an extension with a *-homomorhism into Q analytic methods have to be supplemented by methods coming from algebraic topology, homological algebra, and (more recently) logic.After briefly introducing the BDF theory, I will move to coronas of separable C*-algebras (of which Q is the simplest example) and question of their rigidity. Much attention will be given to the (still half-open) question of Brown-Douglas-Fillmore, whether Q has an automorphism that flips the Fredholm index. This talk will be partially based on the preprint Farah, I., Ghasemi, S., Vaccaro, A., and Vignati, A. (2022). Corona rigidity. arXiv preprint arXiv:2201.11618.
 
Напомена: Предавања се могу пратити на даљину преко линка:
https://miteam.mi.sanu.ac.rs/call/T9XDGChhq8aDcNqmz/qw7wIwci2jv2rdg9I9CrXkm7OJhF_LB8DfjXZp4jTFV
 
Регистрациона форма је доступна на:
https://miteam.mi.sanu.ac.rs/asset/tz97w4Hu4c3unsJ7N