Estimados compañeros, el próximo viernes 7 de abril a las 11 y media en el seminario del IUMPA el profesor Radoslaw Szwedek, de la Adam Mickiewicz University in Poznan (Poland), impartirá la charla “Entropy, spectra and width numbers of operators”

Estáis todos invitados.
In this talk, we will discuss some recent results concerning modern topics in the theory of operators on Banach spaces. We introduce and study entropy and
spectral moduli of operators and show relationships between these moduli and eigenvalues of operators. In particular, some of the obtained formulas may be regarded as a generalization of Gelfand’s spectral radius formula. Combining our results with interpolation techniques yields an interpolation variant of
the famous Carl-Triebel inequality.

It turns out that $s$-numbers of operators between Hilbert spaces behave well under the complex interpolation. This is in contrast to the situation in Banach spaces, where by examples of Carl these numbers do not interpolate well. In particular, we present an interpolation type estimate of approximation numbers as well as some connected results on normal operators.