# Seminars

The department has active seminars in all active research areas.  Inquire with someone from the research area to get on a seminar mailing list.

Some upcoming seminars of note:

Thursday, Sep. 29, 9:00-9:50 AM, BAC 110 (to be confirmed)

Speaker: Przemyslaw Ohrysko, Polish Academy of Sciences, Warsaw, Poland

Title: Non-separability of the Gelfand space of measure algebras

Abstract: We prove that there exists uncountably many pairwise disjoint open subsets of the Gelfand space of the measure algebra on any locally compact non-discrete abelian group which shows that this space is not separable (in fact, we prove this assertion for the ideal M0(G) consisting of measures with Fourier-Stieltjes transforms vanishing at infinity which is a stronger statement). As a corollary, we obtain that the spectras of elements in the algebra of measures cannot be recovered from the image of one countable subset of the Gelfand space under Gelfand transform, common for all elements in the algebra.

(joint work with M. Wojciechowski and Colin C. Graham)

Preprint available at https://arxiv.org/abs/1603.05864

Friday, Sep. 30, 10:00-10:50 AM, BAC 120

Speaker: Krystian Kazaniecki

Title: On the equivalence between the sets of the trigonometric polynomials

In this paper we construct an injection from the linear space of trigonometric polynomials defined on $T^d$ with bounded degrees with respect to each variable to a suitable linear subspace $L^1_E⊂L^1(T)$. We give such a quantitative condition on $L^1_E$ that this injection is a isomorphism of a Banach spaces equipped with $L^1$ norm and the norm of the isomorphism is independent on the dimension d.

(joint work with M. Wojciechowski)

Preprint available at https://arxiv.org/abs/1502.05994