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We study the problem of the integral geometry, in which the functions are integrated over hyperplanes in the $n$-dimensional Euclidean space, $n=2m+1$. The integrand is the product of a function of $n$ variables called the density and…

Mathematical Physics · Physics 2023-09-15 D. S. Anikonov , S. G. Kazantsev , D. S. Konovalova

This article first introduces the notion of weighted singular value decomposition (WSVD) of a tensor via the Einstein product. The WSVD is then used to compute the weighted Moore-Penrose inverse of an arbitrary-order tensor. We then define…

Numerical Analysis · Mathematics 2025-08-07 Aaisha Be , Vaibhav Shekhar , Debasisha Mishra

In this work, we construct an explicit, theoretically rigorous deconvolution method that relies entirely on iterative forward convolutions, thus can be numerically implemented. We first prove that convolution with an even Schwartz kernel…

Signal Processing · Electrical Eng. & Systems 2026-04-20 Alfredo González-Calvin

We consider the problem of decomposing a real-valued symmetric tensor as the sum of outer products of real-valued vectors. Algebraic methods exist for computing complex-valued decompositions of symmetric tensors, but here we focus on…

Numerical Analysis · Mathematics 2018-08-23 Tamara G. Kolda

We study the geodesic X-ray transform on Cartan-Hadamard manifolds, and prove solenoidal injectivity of this transform acting on functions and tensor fields of any order. The functions are assumed to be exponentially decaying if the…

Differential Geometry · Mathematics 2019-09-06 Jere Lehtonen , Jesse Railo , Mikko Salo

The 4D Maxwell theory with single-sided planar boundary is considered. As a consequence of the presence of the boundary, two broken Ward identities are recovered, which, on-shell, give rise to two conserved currents living on the edge. A…

High Energy Physics - Theory · Physics 2020-07-08 Erica Bertolini , Nicola Maggiore

In this paper, partly based on Zachos' PhD thesis, we show that the geodesic X-ray transform is stably invertible near infinity on a class of asymptotically conic manifolds which includes perturbations of Euclidean space. In particular…

Differential Geometry · Mathematics 2024-10-02 András Vasy , Evangelie Zachos

High-dimensional data in the form of tensors are challenging for kernel classification methods. To both reduce the computational complexity and extract informative features, kernels based on low-rank tensor decompositions have been…

Machine Learning · Statistics 2023-02-17 Kirandeep Kour , Sergey Dolgov , Peter Benner , Martin Stoll , Max Pfeffer

We show injectivity of the geodesic X-ray transform on piecewise constant functions when the transform is weighted by a continuous matrix weight. The manifold is assumed to be compact and nontrapping of any dimension, and in dimension three…

Differential Geometry · Mathematics 2020-10-23 Joonas Ilmavirta , Jesse Railo

In this paper, a restricted transverse ray transform acting on vector and symmetric $m$-tensor fields is studied. We developed inversion algorithms using restricted transverse ray transform data to recover symmetric $m$-tensor fields in…

Classical Analysis and ODEs · Mathematics 2024-02-28 Rohit Kumar Mishra , Chandni Thakkar

We study embeddings and norm estimates for tensor products of weighted reproducing kernel Hilbert spaces. These results lead to a transfer principle that is directly applicable to tractability studies of multivariate problems as integration…

Numerical Analysis · Mathematics 2021-09-21 Michael Gnewuch , Mario Hefter , Aicke Hinrichs , Klaus Ritter

The aim of this paper is to study the Wold-type decomposition in the class of $m$-isometries. One of our main results establishes an equivalent condition for an analytic $m$-isometry to admit the Wold-type decomposition for $m\ge2$. In…

Functional Analysis · Mathematics 2021-07-08 Jakub Kośmider

We extend the classical Mercer theorem to reproducing kernel Hilbert spaces whose elements are functions from a measurable space $X$into $\mathbb C^n$. Given a finite measure $\mu$ on $X$, we represent the reproducing kernel $K$ as…

Functional Analysis · Mathematics 2011-10-19 Ernesto De Vito , Veronica Umanita` , Silvia Villa

This article studies the problem of approximating functions belonging to a Hilbert space $H_d$ with an isotropic or anisotropic Gaussian reproducing kernel, $$ K_d(\bx,\bt) = \exp\left(-\sum_{\ell=1}^d\gamma_\ell^2(x_\ell-t_\ell)^2\right) \…

Numerical Analysis · Mathematics 2015-01-16 Gregory E. Fasshauer , Fred J. Hickernell , Henryk Woźniakowski

The ray transform $I_m$ integrates a symmetric $m$ rank tensor field $f$ on $\mathbb{R}^n$ over lines. In the case of $n\ge3$, the range characterization of the operator $I_m$ on weighted Sobolev spaces $H^{s}_t({{\mathbb R}}^n;S^m{{\mathbb…

Analysis of PDEs · Mathematics 2025-09-04 Divyansh Agrawal , Venkateswaran P. Krishnan , Vladimir A. Sharafutdinov

Let $M$ be the space of real $n\times m$ matrices which can be identified with the Euclidean space $R^{nm}$. We introduce continuous wavelet transforms on $M$ with a multivalued scaling parameter represented by a positive definite symmetric…

Functional Analysis · Mathematics 2007-05-23 G. Olafsson , E. Ournycheva , B. Rubin

Let $M$ be an odd-dimensional Euclidean space endowed with a contact 1-form $\alpha$. We investigate the space of symmetric contravariant tensor fields on $M$ as a module over the Lie algebra of contact vector fields, i.e. over the Lie…

Differential Geometry · Mathematics 2015-06-26 Yael Fregier , Pierre Mathonet , Norbert Poncin

In this paper we show that any hypersurface singularities of germs of varieties in positive characteristic can be resolved by iterated monoidal transformations in centers in smooth subvarieties, if we have a valuation ring of iterated…

Algebraic Geometry · Mathematics 2010-06-21 Tohsuke Urabe

We study singular integral operators with kernels that are more singular than standard Calder\'on-Zygmund kernels, but less singular than bi-parameter product Calder\'on-Zygmund kernels. These kernels arise as restrictions to two dimensions…

Classical Analysis and ODEs · Mathematics 2022-03-30 Tuomas Hytönen , Kangwei Li , Henri Martikainen , Emil Vuorinen

We prove that the geodesic X-ray transform is injective on $L^2$ when the Riemannian metric is simple but the metric tensor is only finitely differentiable. The number of derivatives needed depends explicitly on dimension, and in dimension…

Analysis of PDEs · Mathematics 2023-09-25 Joonas Ilmavirta , Antti Kykkänen , Kelvin Lam