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Given a compact Lie group $G$, in this paper we establish $L^p$-bounds for pseudo-differential operators in $L^p(G)$. The criteria here are given in terms of the concept of matrix symbols defined on the non-commutative analogue of the phase…

Analysis of PDEs · Mathematics 2017-01-17 Julio Delgado , Michael Ruzhansky

We study invariants under gauge transformations of linear partial differential operators on two variables. Using results of BK-factorization, we construct hierarchy of general invariants for operators of an arbitrary order. Properties of…

Exactly Solvable and Integrable Systems · Physics 2015-06-26 E. Kartashova

We obtain a lower bound for the Lyapunov exponent of a family of discrete Schr\"{o}dinger operators $(Hu)_n=u_{n+1}+u_{n-1}+2a_1\cos2\pi(\theta+n\alpha)u_n+2a_2\cos4\pi(\theta+n\alpha)u_n$, that incorporates both $a_1$ and $a_2,$ thus going…

Mathematical Physics · Physics 2018-04-24 Svetlana Jitomirskaya , Wencai Liu

We investigate microlocal properties of partial differential operators with generalized functions as coefficients. The main result is an extension of a corresponding (microlocalized) distribution theoretic result on operators with smooth…

Analysis of PDEs · Mathematics 2007-05-23 Guenther Hoermann , Michael Oberguggenberger , Stevan Pilipovic

We consider the third order operator with small 1-periodic coefficients on the real line. The spectrum of the operator is absolutely continuous and covers all real line. Under the minimal conditions on the coefficients we show that there…

Mathematical Physics · Physics 2011-05-19 Andrey Badanin , Evgeny Korotyaev

Let G:=-((d/dx)^2+x^2(d/du)^2) denote the Grusin operator on R^2. Consider the Cauchy problem for the associated wave equation on R x R^2, given by ((d/dt)^2+G)v =0, v(0,.)=f, d/dt v(0,.)=g, where t denotes time and f, g are suitable…

Analysis of PDEs · Mathematics 2007-09-17 Ralf Meyer

Some algebraic, geometric and geometroalgebraic characteristics of pairs of operators are discussed.

funct-an · Mathematics 2008-02-03 Denis Juriev

We prove uniform $L^p$ bounds for multilinear operators which are given by multipliers whose symbols are singular on a one dimensional subspace. The novelty is that these bounds are uniform in the choice of the subspace.

Classical Analysis and ODEs · Mathematics 2007-05-23 Camil Muscalu , Terence Tao , Christoph Thiele

We get the sharp bound for weak type $(1,1)$ inequality for $n$-dimensional Hardy operator. Moreover, the precise norms of generalized Hardy operators on the type of Campanato spaces are obtained. As applications, the corresponding norms of…

Functional Analysis · Mathematics 2021-11-09 Fayou Zhao , Zunwei Fu , Shanzhen Lu

We establish the various properties as well as diverse relations of the ascent and descent spectra for bounded linear operators. We specially focus on the theory of subspectrum. Furthermore, we construct a new concept of convergence for…

Functional Analysis · Mathematics 2018-08-27 Nassim Athmouni , Mondher Damak , Chiraz Jendoubi

We investigate the global boundedness of Fourier integral operators with amplitudes in the general H\"ormander classes $S^{m}_{\rho, \delta}(\mathbb{R}^n)$, $\rho, \delta\in [0,1]$ and non-degenerate phase functions of arbitrary rank…

Analysis of PDEs · Mathematics 2023-09-13 Anders Israelsson , Tobias Mattsson , Wolfgang Staubach

We prove $l^p$-improving estimates for the averaging operator along the discrete paraboloid in the sharp range of $p$ in all dimensions $n\ge 2$.

Classical Analysis and ODEs · Mathematics 2020-02-28 Shival Dasu , Ciprian Demeter , Bartosz Langowski

Building on arXiv:1902.03807, this paper develops a unifying study on the boundedness properties of several representative classes of hybrid operators, i.e. operators that enjoy both zero and non-zero curvature features. Specifically, via…

Classical Analysis and ODEs · Mathematics 2024-02-07 Alejandra Gaitan , Victor Lie

In this note we consider weighted conditional type operators between different Orlicz spaces and generalized conditional type Holder inequality that we defined in [2]. Then we give some necessary and sufficient conditions for boundedness of…

Functional Analysis · Mathematics 2015-02-12 Yousef Estaremi

In this short note, we propose to extend differentiability (with respect to a multidimensional parameter) of a normalized eigenfunction associated to the simple, dominating eigenvalue of the weighted transfer operator for a uniformly…

Dynamical Systems · Mathematics 2018-10-12 Julien Sedro

In this paper, Hardy's uncertainty principle and unique continuation properties of Schrodinger equations with operator potentials in Hilbert space-valued classes are obtained. Since the Hilbert space H and linear operators are arbitrary, by…

Analysis of PDEs · Mathematics 2019-06-04 Veli Shakhmurov

In this paper we study the mapping properties of the averaging operator over a variety given by a system of homogeneous equations over a finite field. We obtain optimal results on the averaging problems over two dimensional varieties whose…

Functional Analysis · Mathematics 2013-04-11 Doowon Koh , Chun-Yen Shen , Igor Shparlinski

We analyze spectral properties of a family of self-adjoint first-order finite difference operators acting on $\ell^2(\mathbb{Z}; \mathbb{C}^2)$ or $\ell^2(\mathbb{Z}_+; \mathbb{C}^2)$. Applying the conjugate operator method, we prove the…

Spectral Theory · Mathematics 2025-11-04 Olivier Bourget , Angela Vargas-Mancipe

In this note we extend two characterizations of admissible operators with respect to $\mathrm{L}^p$ to more general Orlicz spaces. The equivalent conditions are given by the property that an associated operator generates a strongly…

Functional Analysis · Mathematics 2022-08-01 René Hosfeld , Birgit Jacob , Felix L. Schwenninger

Length generalization is a key property of a learning algorithm that enables it to make correct predictions on inputs of any length, given finite training data. To provide such a guarantee, one needs to be able to compute a length…

Machine Learning · Computer Science 2026-03-04 Andy Yang , Pascal Bergsträßer , Georg Zetzsche , David Chiang , Anthony W. Lin