Harmonic analysis for vector fields on hyperbolic spaces

We acknowledge the support by the Swiss National Science Foundation     

On vector spaces over specific fields without choice

We investigate the deductive strength of statements concerning vector spaces over specific fields in the hierarchy of various choice principles.     

Polynomials in topological vector spaces over valued fields

We consider the vector space of continuousm-homogeneous polynomials between topological vector spaces over a non-trivially valued field of characteristic zero and certain natural vector topologies on such spaces, and we prove polynomial versions of certain well known theorems of the linear theory of locally convex spaces. Partially supported by CNPq.     

Chains of function spaces over Euclidian spaces and local fields

The Lipschitz class Lip(K, α) on a local field K is defined in [10], and an equivalent relationship between the Ho¨lder type space Cα(K)[9] and Lip(K,α) is given. In this note, we give a “chain of function spaces“ over Euclidian space by defining higher order continuous modulus in R, and point out that there is no need of higher order continuous modulus for describing the chain of function spaces over local fields.     

Paley-like graphs over finite fields from vector spaces

Motivated by the well-known Paley graphs over finite fields and their generalizations, in this paper we explore a natural multiplicative-additive analogue of such graphs arising from vector spaces over finite fields. Namely, if $n\ge 2$ and $U⊊{\mathbb{F}}_{q^n}$ is an ${\mathbb{F}}_q$-vector space, $G_U$ is the (undirected) graph with vertex set $V(G_U)={\mathbb{F}}_{q^n}$ and edge set $E(G_U)=\{(a,b)\in {\mathbb{F}}_{q^n}^2|a\ne b,ab\in U\}$. We describe the structure of an arbitrary maximal clique in $G_U$ and provide bounds on the clique number $\omega (G_U)$ of $G_U$. In particular, we compute the largest possible value of $\omega (G_U)$ for arbitrary q and n. Moreover, we obtain the exact value of $\omega (G_U)$ when $U⊊{\mathbb{F}}_{q^n}$ is any ${\mathbb{F}}_q$-vector space of dimension $d_U\in \{1,2,n-1\}$.     

Multipliers on Herz type Hardy spaces over local fields

In this paper, we establish two multiplier theorems for Herz type Hardy spaces, and as an application, we discuss the boundedness of pseudo-differential operators in these spaces.     

Multipliers on Herz type Hardy spaces over local fields

In this paper, we establish two multiplier theorems for Herz type Hardy spaces, and as an application, we discuss the boundedness of pseudo-differential operators in these spaces.     

Ubiquity of simplices in subsets of vector spaces over finite fields

We prove that a sufficiently large subset of the d-dimensional vector space over a finite field with q elements, $ \mathbb{F} $ _q ^d , contains a copy of every k-simplex. Fourier analytic methods, Kloosterman sums, and bootstrapping play an important role.     

Harmonic vector fields on Landsberg manifolds

Let (M,F)$(M,F)$ be a compact boundaryless Landsberg manifold. In this work, a necessary and sufficient condition for a vector field on (M,F)$(M,F)$ to be harmonic is obtained. Next, on a compact boundaryless Finsler manifold of zero flag curvature, a necessary and sufficient condition for a vector field to be harmonic is found. Furthermore, the nonexistence of harmonic vector fields on a compact Landsberg manifold is studied and an upper bound for the first de Rham cohomology group is obtained.     

Erdös distance problem in vector spaces over finite fields

We study the Erdös/Falconer distance problem in vector spaces over finite fields. Let be a finite field with elements and take , . We develop a Fourier analytic machinery, analogous to that developed by Mattila in the continuous case, for the study of distance sets in to provide estimates for minimum cardinality of the distance set in terms of the cardinality of . Bounds for Gauss and Kloosterman sums play an important role in the proof.

     

Function spaces on local fields

We study the function spaces on local fields in this paper, such as Triebel B-type and F-type spaces, Holder type spaces, Sobolev type spaces, and so on, moreover, study the relationship between the p-type derivatives and the Holder type spaces. Our obtained results show that there exists quite difference between the functions defined on Euclidean spaces and local fields, respectively. Furthermore, many properties of functions defined on local fields motivate the new idea of solving some important topics on fractal analysis.     

Monotonic analysis over ordered topological vector spaces: IV

In this paper, we present an extension for non-negative increasing and co-radiant (ICR) functions over a topological vector space. We characterize the essential results of abstract convexity such as support set, subdifferential and polarity of these functions. We also give some characterizations of a certain kind of polarity and separation property for non-convex radiant and co-radiant sets.