Results 61 to 70 of about 27,509 (180)

Distributional asymptotic expansions of spectral functions and of the associated Green kernels

Electronic Journal of Differential Equations, 1999
Asymptotic expansions of Green functions and spectral densities associated with partial differential operators are widely applied in quantum field theory and elsewhere.
R. Estrada, S. A. Fulling
doaj  

Fractional Fourier Series on the Torus and Applications

Fractal and Fractional
This paper introduces the fractional Fourier series on the fractional torus and proceeds to investigate several fundamental aspects. Our study includes topics such as fractional convolution, fractional approximation, fractional Fourier inversion, and the
Chen Wang, Xianming Hou, Qingyan Wu, Pei Dang, Zunwei Fu   +4 more
doaj   +1 more source

Riesz means and Greedy Sums

, 2012
One introduces the concept of greedy k-summability in such a way, that the direct product of one greedy k-summable numeric array onto another greedy n-summable numeric array to be greedy (n+k+1)-summable.
openaire   +2 more sources

Discrete analogues of second‐order Riesz transforms

Journal of the London Mathematical Society, Volume 113, Issue 3, March 2026.
Abstract Discrete analogues of classical operators in harmonic analysis have been widely studied, revealing deep connections with areas such as ergodic theory and analytic number theory. This line of research is commonly known as Discrete Analogues in Harmonic Analysis (DAHA).
Rodrigo Bañuelos, Daesung Kim
wiley   +1 more source

Potential trace inequalities via a Calderón‐type theorem

Journal of the London Mathematical Society, Volume 113, Issue 3, March 2026.
Abstract In this paper, we develop a general theoretical tool for the establishment of the boundedness of notoriously difficult operators (such as potentials) on certain specific types of rearrangement‐invariant function spaces from analogous properties of operators that are easier to handle (such as fractional maximal operators).
Zdeněk Mihula, Luboš Pick, Daniel Spector   +2 more
wiley   +1 more source

The weak (1,1) boundedness of Fourier integral operators with complex phases

Journal of the London Mathematical Society, Volume 113, Issue 3, March 2026.
Abstract Let T$T$ be a Fourier integral operator of order −(n−1)/2$-(n-1)/2$ associated with a canonical relation locally parametrised by a real‐phase function. A fundamental result due to Seeger, Sogge and Stein proved in the 90's gives the boundedness of T$T$ from the Hardy space H1$H^1$ into L1$L^1$. Additionally, it was shown by T.
Duván Cardona, Michael Ruzhansky
wiley   +1 more source

Bounds on Riesz Means of the Eigenvalues for Baouendi–Grushin Type Operators

International Journal of Mathematics and Mathematical Sciences
The aim of this paper is to consider spectral inequalities of a class of Baouendi–Grushin type operators in cylinders. Such operators are hypoelliptic and we obtain non-Weyl type inequalities depending on the rate of the degeneracy.
Alaa Aljahili, Ari Laptev
doaj   +1 more source

On the Riesz Means of Expansions by Riesz Bases Formed by Eigenfunctions for the Ordinary Differential Operator of 4-th Order

Ibn Al-Haitham Journal for Pure and Applied Sciences, 2017
The aim of this paper is prove a theorem on the Riesz mean of expansions with respect to Riesz bases, which extends the previous results of Loi and Tahir on the Schrodinger operator to the operator of 4-th order.
M. B. Tahir, A. A. Aswhad
doaj  

Spectral Riesz-Cesaro means: How the square root function helps us to see around the world

Electronic Journal of Differential Equations, 2000
The heat-kernel expansion for a nonanalytic function of a differential operator, and the integrated (Cesàro-smoothed) spectral densities associated with the corresponding nonanalytic function of the spectral parameter, exhibit a certain nonlocal ...
S. A. Fulling, E. V. Gorbar, C. T. Romero   +2 more
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