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Using the machinery of unitary spherical harmonics due to Koornwinder, Folland and other authors, we~obtain expansions for the Szeg\"o and the weighted Bergman kernels of $M$-harmonic functions, i.e.~functions annihilated by the invariant…

Complex Variables · Mathematics 2022-08-16 Miroslav Englis , El-Hassan Youssfi

In this article, we study the properties of the geodesic X-ray transform for asymptotically Euclidean or conic Riemannian metrics and show injectivity under non-trapping and no conjugate point assumptions. We also define a notion of lens…

Differential Geometry · Mathematics 2021-02-09 Colin Guillarmou , Matti Lassas , Leo Tzou

We consider integral geometry inverse problems for unitary connections and skew-Hermitian Higgs fields on manifolds with negative sectional curvature. The results apply to manifolds in any dimension, with or without boundary, and also in…

Analysis of PDEs · Mathematics 2016-01-20 Colin Guillarmou , Gabriel P. Paternain , Mikko Salo , Gunther Uhlmann

Differential geometric approaches to the analysis and processing of data in the form of symmetric positive definite (SPD) matrices have had notable successful applications to numerous fields including computer vision, medical imaging, and…

Differential Geometry · Mathematics 2024-06-10 Cyrus Mostajeran , Nathaël Da Costa , Graham Van Goffrier , Rodolphe Sepulchre

The mechanism of describing quantum states by standard probability (tomographic one) instead of wave function or density matrix is elucidated. Quantum tomography is formulated in an abstract Hilbert space framework, by means of the identity…

Quantum Physics · Physics 2008-11-26 V. I. Man'ko , G. Marmo , A. Simoni , A. Stern , E. C. G. Sudarshan , F. Ventriglia

This article studies the problem of approximating functions belonging to a Hilbert space $\mathcal H_d$ with a reproducing kernel of the form $$\tilde K_d(\boldsymbol x,\boldsymbol t):=\prod_{\ell=1}^d…

Numerical Analysis · Mathematics 2014-11-05 Xuan Zhou , Fred J. Hickernell

For smooth compact connected manifolds with strictly convex boundary, no conjugate points and a hyperbolic trapped set, we prove an equivalence principle concerning the injectivity of the X-ray transform $I_m$ on symmetric solenoidal…

Analysis of PDEs · Mathematics 2019-08-08 Thibault Lefeuvre

We use methods of algebraic geometry to find new, effective methods for detecting the identifiability of symmetric tensors. In particular, for ternary symmetric tensors T of degree 7, we use the analysis of the Hilbert function of a finite…

Algebraic Geometry · Mathematics 2019-07-23 Elena Angelini , Luca Chiantini , Andrea Mazzon

This article surveys recent results aiming at obtaining refined mapping estimates for the X-ray transform on a Riemannian manifold with boundary, which leverage the condition that the boundary be strictly geodesically convex. These…

Analysis of PDEs · Mathematics 2023-09-04 François Monard

Let $\mathscr T$ be a rooted directed tree with finite branching index $k_{\mathscr T}$ and let $S_{\lambda} \in B(l^2(V))$ be a left-invertible weighted shift on ${\mathscr T}$. We show that $S_{\lambda}$ can be modelled as a…

Functional Analysis · Mathematics 2017-05-17 Sameer Chavan , Shailesh Trivedi

We realize the relative discrete series of a weighted $L^2$-space on a bounded symmetric doamin as kernels of invariant Cauchy-Riemann operator, and thus as the spaces of nearly holomorphic functions.

Representation Theory · Mathematics 2007-05-23 Genkai Zhang

We prove that the geodesic X-ray transform is injective on scalar functions and (solenoidally) on one-forms on simple Riemannian manifolds $(M,g)$ with $g \in C^{1,1}$. In addition to a proof, we produce a redefinition of simplicity that is…

Differential Geometry · Mathematics 2023-04-12 Joonas Ilmavirta , Antti Kykkänen

Consider the product of $M$ quadratic random matrices with complex elements and no further symmetry, where all matrix elements of each factor have a Gaussian distribution. This generalises the classical Wishart-Laguerre Gaussian Unitary…

Mathematical Physics · Physics 2013-06-28 Gernot Akemann , Mario Kieburg , Lu Wei

We study the variation of weighted Szeg\H{o} and Garabedian kernels on planar domains as a function of the weight. A Ramadanov type theorem is shown to hold as the weights vary. As a consequence, we derive properties of the zeros of the…

Complex Variables · Mathematics 2025-08-20 Aakanksha Jain , Kaushal Verma

We study the Pareto frontier for two competing norms $\|\cdot\|_X$ and $\|\cdot\|_Y$ on a vector space. For a given vector $c$, the pareto frontier describes the possible values of $(\|a\|_X,\|b\|_Y)$ for a decomposition $c=a+b$. The…

Numerical Analysis · Mathematics 2017-06-01 Harm Derksen

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

This article extends the author's past work [Inv. Probl. Imaging, 10:2 (2016), 433--459] to attenuated X-ray transforms, where the attenuation is complex-valued and only depends on position. We give a positive and constructive answer to the…

Analysis of PDEs · Mathematics 2017-11-03 François Monard

The development of energy selective, photon counting X-ray detectors allows for a wide range of new possibilities in the area of computed tomographic image formation. Under the assumption of perfect energy resolution, here we propose a…

Computer Vision and Pattern Recognition · Computer Science 2015-06-16 Oguz Semerci , Ning Hao , Misha E. Kilmer , Eric L. Miller

We give a Riemannian structure to the set $\Sigma$ of positive invertible unitized Hilbert-Schmidt operators, by means of the trace inner product. This metric makes of $\Sigma$ a nonpositively curved, simply connected and metrically…

Differential Geometry · Mathematics 2008-08-20 Gabriel Larotonda

The eleven-dimensional gravitational action invariant under local Poincare transformations is given by the dimensional continuation of the Euler class of ten dimensions. Here we show that the supersymmetric extension of this action leads,…

High Energy Physics - Theory · Physics 2007-05-23 Mokhtar Hassaine , Ricardo Troncoso , Jorge Zanelli
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