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Classical noncompact reductive Lie group $G$ admits a compactification $\overline{G}$ as a Riemannian symmetric space by He. First, we provide a unified construction of these compactifications via Grassmannian geometry and realize the group…

Differential Geometry · Mathematics 2026-02-03 Yunxia Chen , Naichung Conan Leung

Using the matrix representation of Fourier integral operators with respect to a Gabor frame, we study their compactness on weighted modulation spaces. As a consequence, we recover and improve some compactness results for pseudodifferential…

Functional Analysis · Mathematics 2017-10-18 Carmen Fernández , Antonio Galbis , Eva Primo

We study integration over functions on superspaces. These functions are invariant under a transformation which maps the whole superspace onto the part of the superspace which only comprises purely commuting variables. We get a compact…

Mathematical Physics · Physics 2009-02-05 Mario Kieburg , Heiner Kohler , Thomas Guhr

We introduce a new approach to the anisotropic Calder\'on problem, based on a map called Poisson embedding that identifies the points of a Riemannian manifold with distributions on its boundary. We give a new uniqueness result for a large…

Analysis of PDEs · Mathematics 2019-04-05 Matti Lassas , Tony Liimatainen , Mikko Salo

We propose to relax the classic Cauchy-Riemann equations for a mapping. We support the interest of such a proposal by looking at one specific situation in 3D, and proving the existence of pairs of harmonic conjugate functions with respect…

Analysis of PDEs · Mathematics 2025-02-14 Pablo Pedregal

We present a categorical formulation of the Hamiltonian renormalisation programme for quantum field theories, establishing a systematic bridge between functional and lattice renormalisation. To this end, we introduce two categories, $Seq$…

General Relativity and Quantum Cosmology · Physics 2025-11-20 M. Rodriguez Zarate

The objet of this paper is the study of the variations of a functional whose integrant is the r-th weighted curvature on the hypersurface of a closed Riemannian manifold. Some applications to hypersurfaces of the Euclidean space and the…

Differential Geometry · Mathematics 2020-07-30 Mohammed Benalili

We prove the integrability and superintegrability of a family of natural Hamiltonians which includes and generalises those studied in some literature, originally defined on the 2D Minkowski space. Some of the new Hamiltonians are a perfect…

Mathematical Physics · Physics 2020-06-12 Claudia Maria Chanu , Giovanni Rastelli

In this paper we study eigenvalues of the closed eigenvalue problem of the Witten-Laplacian on an $n$-dimensional compact Riemannian manifold. Estimates for eigenvalues are given. As applications, we give a sharp upper bound for the…

Differential Geometry · Mathematics 2017-01-08 Qing-Ming Cheng , Lingzhong Zeng

The convergence of the so-called quadratic method for computing eigenvalue enclosures of general self-adjoint operators is examined. Explicit asymptotic bounds for convergence to isolated eigenvalues are found. These bounds turn out to…

Numerical Analysis · Mathematics 2016-11-26 Lyonell Boulton , Aatef Hobiny

We consider spaces of holomorphic functions which are square-integrable against a Gaussian weight, which appear in the theory of metaplectic FBI--Bargmann transforms. We identify the operator norm of embeddings between two such spaces, by…

Analysis of PDEs · Mathematics 2022-09-28 Joe Viola

We establish explicit formulae for canonical factorizations of extended solutions corresponding to harmonic maps of finite uniton number into the exceptional Lie group $G_2$ in terms of the Grassmannian model for the group of based…

Differential Geometry · Mathematics 2010-07-27 N. Correia , R. Pacheco

We study several integrable Hamiltonian systems on the moduli spaces of meromorphic functions on Riemann surfaces (the Riemann sphere, a cylinder and a torus). The action-angle variables and the separated variables (in Sklyanin's sense) are…

Exactly Solvable and Integrable Systems · Physics 2015-06-26 Kanehisa Takasaki , Takashi Takebe

We introduce a simple, general, and convergent scheme to compute generalized eigenfunctions of self-adjoint operators with continuous spectra on rigged Hilbert spaces. Our approach does not require prior knowledge about the eigenfunctions,…

Numerical Analysis · Mathematics 2024-10-14 Matthew J. Colbrook , Andrew Horning , Tianyiwa Xie

The Wigner-von Neumann method, which was previously used for perturbing continuous Schr\"{o}dinger operators, is here applied to their discrete counterparts. In particular, we consider perturbations of arbitrary $T$-periodic Jacobi…

Functional Analysis · Mathematics 2016-06-03 Edmund Judge , Sergey Naboko , Ian Wood

The factorization technique for superintegrable Hamiltonian systems is revisited and applied in order to obtain additional (higher-order) constants of the motion. In particular, the factorization approach to the classical anisotropic…

Mathematical Physics · Physics 2017-04-18 Angel Ballesteros , Francisco J. Herranz , Sengul Kuru , Javier Negro

Matrix integrals used in random matrix theory for the study of eigenvalues of matrix ensembles have been shown to provide $ \tau $-functions for several hierarchies of integrable equations. In this paper, we construct the matrix integral…

Exactly Solvable and Integrable Systems · Physics 2019-11-22 Bo-Jian Shen , Guo-Fu Yu

This paper focuses on minimizing a smooth function combined with a nonsmooth regularization term on a compact Riemannian submanifold embedded in the Euclidean space under a decentralized setting. Typically, there are two types of approaches…

Optimization and Control · Mathematics 2025-07-16 Lei Wang , Le Bao , Xin Liu

Correlation functions for matrix ensembles with orthogonal and unitarysymplectic rotation symmetry are more complicated to calculate than in the unitary case. The supersymmetry method and the orthogonal polynomials are two techniques to…

Mathematical Physics · Physics 2010-03-19 Mario Kieburg , Thomas Guhr

We prove that, given any knot $\gamma$ in a compact 3-manifold M, there exists a Riemannian metric on M such that there is a complex-valued eigenfunction u of the Laplacian, corresponding to the first nontrivial eigenvalue, whose nodal set…

Spectral Theory · Mathematics 2015-05-26 Alberto Enciso , David Hartley , Daniel Peralta-Salas