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This work concerns the construction and characterization of product kernels for multivariate approximation from a finite set of discrete samples. To this end, we consider composing different component kernels, each acting on a…

Numerical Analysis · Mathematics 2024-11-27 Kristof Albrecht , Juliane Entzian , Armin Iske

A new notion of stochastic germs for quantum processes is introduced and a characterisation of the stochastic differentials for positive definite (PD) processes is found in terms of their germs for arbitrary Ito algebra. A representation…

Probability · Mathematics 2007-05-23 V. P. Belavkin

We construct a generalization of the multiplicative product of distributions presented by L. H\"ormander in [L. H\"ormander, {\it The analysis of linear partial differential operators I} (Springer-Verlag, 1983)]. The new product is defined…

Functional Analysis · Mathematics 2009-07-14 Nuno Costa Dias , Joao Nuno Prata

We describe positive generalized functionals in Gaussian Analysis. We focus on distribution spaces larger than the space of Hida Distributions. It is shown that a positive distribution is represented by a measure with specific growth of its…

Functional Analysis · Mathematics 2007-05-23 Yuri G. Kondratiev , Ludwig Streit , Werner Westerkamp

The first representation theorem establishes a correspondence between positive, self-adjoint operators and closed, positive forms on Hilbert spaces. The aim of this paper is to show that some of the results remain true if the underlying…

Functional Analysis · Mathematics 2007-05-23 Balint Farkas , Mate Matolcsi

We construct differential algebras in which spaces of (one-dimensional) periodic ultradistributions are embedded. By proving a Schwartz impossibility type result, we show that our embeddings are optimal in the sense of being consistent with…

Functional Analysis · Mathematics 2017-10-12 Andreas Debrouwere

As follows from the Schwartz Impossibility Theorem, multiplication of two distributions is in general impossible. Nevertheless, often one needs to multiply a distribution by a discontinuous function, not by an arbitrary distribution. In the…

Classical Analysis and ODEs · Mathematics 2007-05-23 V. Derr , D. Kinzebulatov

We continue our study and applications of generalized H\"ormander spaces of distributions $\mathcal{D}'_{\gamma,\Lambda}$ with $C^\infty$ wavefront set included in a cone $\Lambda$ and the union of $H^s$-wave front sets in a second cone…

Mathematical Physics · Physics 2014-12-05 Yoann Dabrowski

Let $\Omega\subset\mathbb{R}^n$ be an open, connected subset of $\mathbb{R}^n$, and let $F\colon\Omega-\Omega\to\mathbb{C}$, where $\Omega-\Omega=\{x-y\colon x,y\in\Omega\}$, be a continuous positive definite function. We give necessary and…

Spectral Theory · Mathematics 2014-01-03 Palle Jorgensen , Robert Niedzialomski

A recognized trend of research investigates generalizations of the Hadamard's inversion theorem to functions that may fail to be differentiable. In this vein, the present paper explores some consequences of a recent result about the…

Optimization and Control · Mathematics 2023-09-22 Amos Uderzo

Starting with the correspondence between positive definite kernels on the one hand and reproducing kernel Hilbert spaces (RKHSs) on the other, we turn to a detailed analysis of associated measures and Gaussian processes. Point of departure:…

Functional Analysis · Mathematics 2019-02-26 Palle Jorgensen , Feng Tian

We study embeddings between reproducing kernel Hilbert spaces $H(K)$ of functions of $d \in \mathbb{N} \cup \{\infty\}$ variables. The kernels $K$ are superpositions of weighted finite tensor products of a fixed univariate kernel. The basic…

Numerical Analysis · Mathematics 2026-05-01 Michael Gnewuch , Peter Kritzer , Klaus Ritter

A definition for elliptical tempered stable distribution, based on the characteristic function, have been explained which involve a unique spectral measure. This definition provides a framework for creating a connection between infinite…

Probability · Mathematics 2014-08-18 Hassan A. Fallahgoul , Young S. Kim

We introduce and study the notions of translation bounded tempered distributions, and autocorrelation for a tempered distrubution. We further introduce the spaces of weakly, strongly and null weakly almost periodic tempered distributions…

Mathematical Physics · Physics 2017-06-06 Nicolae Strungaru , Venta Terauds

We investigate Bochner integrabilities of generalized Wiener functionals. We further formulate an It\^o formula for a diffusion in a distributional setting, and apply to investigate differentiability-index $s$ and integrability-index $p…

Probability · Mathematics 2018-09-18 Takafumi Amaba , Yoshihiro Ryu

We develop the theory of categories of measurable fields of Hilbert spaces and bounded fields of bounded operators. We examine classes of functors and natural transformations with good measure theoretic properties, providing in the end a…

Category Theory · Mathematics 2007-05-23 D. N. Yetter

In this paper we prove existence and pathwise uniqueness for a class of stochastic differential equations (with coefficients $\sigma_{ij},b_i$ and initial condition $y$ in the space of tempered distributions) that maybe viewed as a…

Probability · Mathematics 2017-06-29 B. Rajeev

The prime aim of the present paper is to continue developing the theory of tempered fractional integrals and derivatives of a function with respect to another function. This theory combines the tempered fractional calculus with the…

Classical Analysis and ODEs · Mathematics 2022-11-23 Ashwini D. Mali , Kishor D. Kucche , Arran Fernandez , Hafiz Muhammad Fahad

We investigate the structure of the Schrodinger algebra and its representations in a Fock space realized in terms of canonical Appell systems. Generalized coherent states are used in the construction of a Hilbert space of functions on which…

Mathematical Physics · Physics 2015-06-26 Ph. Feinsilver , J. Kocik , R. Schott

Inspired by the theories of Kaplansky-Hilbert modules and probability theory in vector lattices, we generalise functional analysis by replacing the scalars $\mathbb{R}$ or $\mathbb{C}$ by a real or complex Dedekind complete unital…