9,408 research outputs found
Approximation of Entropy Numbers
The purpose of this article is to develop a technique to estimate certain
bounds for entropy numbers of diagonal operator on spaces of p-summable
sequences for finite p greater than 1. The approximation method we develop in
this direction works for a very general class of operators between Banach
spaces, in particular reflexive spaces. As a consequence of this technique we
also obtain that the entropy number of a bounded linear operator T between two
separable Hilbert spaces is equal to the entropy number of the adjoint of T.
This gives a complete answer to the question posed by B. Carl [4] in the
setting of separable Hilbert spaces.Comment: 10 page
Large cardinals and continuity of coordinate functionals of filter bases in Banach spaces
Assuming the existence of certain large cardinal numbers, we prove that for
every projective filter over the set of natural numbers,
-bases in Banach spaces have continuous coordinate functionals. In
particular, this applies to the filter of statistical convergence, thereby we
solve a problem by V. Kadets (at least under the presence of certain large
cardinals). In this setting, we recover also a result of Kochanek who proved
continuity of coordinate functionals for countably generated filters (Studia
Math., 2012).Comment: 10 p
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