Weak compactness and summability
Weighted means in non-archimedean fields
Weighted Versions of Beurling's Tauberian Theorem.
What should be a rate of convergence ?
When does the Katětov order imply that one ideal extends the other?
We consider the Katětov order between ideals of subsets of natural numbers ("") and its stronger variant-containing an isomorphic ideal ("⊑ "). In particular, we are interested in ideals for which for every ideal . We find examples of ideals with this property and show how this property can be used to reformulate some problems known from the literature in terms of the Katětov order instead of the order "⊑ " (and vice versa).
Wiener amalgams and summability of Fourier series.