Hauptseminar Geometrie

Prof. Dr. Tobias Hartnick, Technion, Haifa, Israel

In the 1950s Ulam suggested a new mathematical field of "quasi-algebra”, where algebraic definitions get modified by allowing algebraic conditions to hold only “up to a small error”. Two of the main objects in the field are quasimorphisms and quasi-states. The former first arose in the 4th century BC in Eudoxus' construction of the real numbers, and found a conceptual framework in the theory of bounded cohomology as developed by Johnson-Traubel-Gromov more than 2300 years later. The latter are closely connected with von Neumann’s axiomatisation of quantum mechanics, but have recently also become an important tool in symplectic topology in connection with displacement rigidity problems. In this talk we will discuss various examples of quasimorphisms and quasi-states and provide various partial classification results, in particular in the context of finite-dimensional Lie groups. The talk should be accessible to everyone from beginning master students.

Freitag, den 10. Oktober 2014 um 13:30 Uhr, in INF 288, HS5 Freitag, den 10. Oktober 2014 at 13:30, in INF 288, HS5

Der Vortrag folgt der Einladung von The lecture takes place at invitation by Prof. A. Wienhard / Dr. D. Alessandrini