A general non-linear convexity theorem.
A generalization of a theorem of Erdős-Rényi to m-fold sums and differences
Let m ≥ 2 be a positive integer. Given a set E(ω) ⊆ ℕ we define to be the number of ways to represent N ∈ ℤ as a combination of sums and differences of m distinct elements of E(ω). In this paper, we prove the existence of a “thick” set E(ω) and a positive constant K such that for all N ∈ ℤ. This is a generalization of a known theorem by Erdős and Rényi. We also apply our results to harmonic analysis, where we prove the existence of certain thin sets.
A generalization of amenability and inner amenability of groups
Let be a locally compact group. We continue our work [A. Ghaffari: -amenability of locally compact groups, Acta Math. Sinica, English Series, 26 (2010), 2313–2324] in the study of -amenability of a locally compact group defined with respect to a closed subgroup of . In this paper, among other things, we introduce and study a closed subspace of and then characterize the -amenability of using . Various necessary and sufficient conditions are found for a locally compact group to possess...
A generalization of Wienner's criteria for the continuity of a Borel measure
A generalized notion of -weak amenability
In the current work, a new notion of -weak amenability of Banach algebras using homomorphisms, namely --weak amenability is introduced. Among many other things, some relations between --weak amenability of a Banach algebra and , the Banach algebra of matrices with entries from , are studied. Also, the relation of this new concept of amenability of a Banach algebra and its unitization is investigated. As an example, it is shown that the group algebra is ()--weakly amenable for any...
A Generalized Orlicz-Pettis Theorem and Applications.
A geometric classification of Lie groups.
This paper is part of a general program that was originally designed to study the Heat diffusion kernel on Lie groups.
A Geometric Construction of the Discrete Series for Semisimple Lie Groups.
A geometrical property of causal invertible systems.
A Hardy inequality with remainder terms in the Heisenberg group and the weighted eigenvalue problem.
A Heat Semigroup Version of Bernstein's Theorem on Lie Groups.
A Helson set of uniqueness but not of synthesis
In [3] I showed that there are Helson sets on the circle 𝕋 which are not of synthesis, by constructing a Helson set which was not of uniqueness and so automatically not of synthesis. In [2] Kaufman gave a substantially simpler construction of such a set; his construction is now standard. It is natural to ask whether there exist Helson sets which are of uniqueness but not of synthesis; this has circulated as an open question. The answer is "yes" and was also given in [3, pp. 87-92] but seems to...
A Hilbert transform for non-homogeneous martingales
A Künneth formula in topological homology and its applications to the simplicial cohomology of
We establish a Künneth formula for some chain complexes in the categories of Fréchet and Banach spaces. We consider a complex of Banach spaces and continuous boundary maps dₙ with closed ranges and prove that Hⁿ(’) ≅ Hₙ()’, where Hₙ()’ is the dual space of the homology group of and Hⁿ(’) is the cohomology group of the dual complex ’. A Künneth formula for chain complexes of nuclear Fréchet spaces and continuous boundary maps with closed ranges is also obtained. This enables us to describe explicitly...
A Large Bi-Invariant Nuclear Function Space on a Locally Compact Group.
A limit relation for Dunkl-Bessel functions of type A and B.
A maximal function on harmonic extensions of -type groups
Let be an -type group and be its harmonic extension. We study a left invariant Hardy–Littlewood maximal operator on , obtained by taking maximal averages with respect to the right Haar measure over left-translates of a family of neighbourhoods of the identity. We prove that the maximal operator is of weak type .
A moment sequence in the q-world
The aim of the paper is to present some initial results about a possible generalization of moment sequences to a so-called q-calculus. A characterization of such a q-analogue in terms of appropriate positivity conditions is also investigated. Using the result due to Maserick and Szafraniec, we adapt a classical description of Hausdorff moment sequences in terms of positive definiteness and complete monotonicity to the q-situation. This makes a link between q-positive definiteness and q-complete...
A multiplier counter-example for mixed-norm spaces
A multiplier theorem for continuous measures