2014

September 9 

Igor Krichever

Pentagram map, Frieze patterns and commuting difference operators

January 21 

Yanqi Qiu (Aix-Marseille Université)

The UMD Constants for Mixed Normed Lebesgue Spaces 

After a short introduction of the unconditional martingale property (UMD property) for Banach spaces, I will give an estimate for the constants appeared in the vector-valued martingales" inequalities for defining this property. This estimate yields in particular a very natural construction of a Banach space (in fact Banach lattice) which is super-reflexive but does not have the UMD property. 

Ilya Shkredov 

On Quantitative Version of Beurling-Helson Theorem