Results 11 to 20 of about 172 (97)

Rational points on even‐dimensional Fermat cubics

open access: yesTransactions of the London Mathematical Society, Volume 13, Issue 1, December 2026.
Abstract We show that even‐dimensional Fermat cubic hypersurfaces are rational over any field of characteristic not equal to three, by constructing explicit rational parameterizations with polynomials of low degree. As a byproduct of our rationality constructions, we obtain estimates for the number of their rational points over a number field and ...
Alex Massarenti
wiley   +1 more source

Good Real Perturbations of Simple Corank One Map Germs From R3$\mathbb {R}^3$ to R3$\mathbb {R}^3$

open access: yesMathematische Nachrichten, Volume 299, Issue 10, Page 2805-2835, October 2026.
ABSTRACT The existence of good real perturbations of map germs is one of the most interesting open questions in singularity theory. In this paper, we investigate this question for all simple corank one map germs from R3$\mathbb {R}^3$ to R3$\mathbb {R}^3$, we give a complete description of those that admit a good real perturbation.
A. J. Miranda, M. J. Saia, T. O. Souza
wiley   +1 more source

Topological and geometric rigidity of nonnegatively curved submanifolds

open access: yesBulletin of the London Mathematical Society, Volume 58, Issue 10, October 2026.
Abstract We investigate the topology and geometry of compact submanifolds in space forms of nonnegative curvature satisfying a lower bound on the sectional curvature that depends only on the length of the mean curvature vector of the immersion. We show that this condition imposes strong constraints on either the topology or geometry of the submanifold.
Theodoros Vlachos
wiley   +1 more source

bk$b^k$‐Algebroids and the variety of foliation jets

open access: yesJournal of the London Mathematical Society, Volume 114, Issue 4, October 2026.
Abstract We introduce and classify singular foliations of bk+1$b^{k+1}$‐type, which formalize the properties of vector fields that are tangent to a submanifold W⊂M$W \subset M$ to order k$k$. When W$W$ is a hypersurface, these structures are Lie algebroids generalizing the bk+1$b^{k+1}$‐tangent bundles introduced by Scott.
Francis Bischoff   +2 more
wiley   +1 more source

Sharp restriction estimates for some degenerate higher codimensional quadratic surfaces

open access: yesJournal of the London Mathematical Society, Volume 114, Issue 4, October 2026.
Abstract The Fourier restriction conjecture is a fundamental problem in harmonic analysis. In this paper, we investigate restriction estimates for degenerate higher codimensional quadratic surfaces and obtain sharp results for some types of degenerate cases.
Zhenbin Cao, Changxing Miao, Yixuan Pang
wiley   +1 more source

Wasserstein rigidity over Rn$\mathbb {R}^n$ with smooth norms

open access: yesMathematika, Volume 72, Issue 4, October 2026.
Abstract We study p−Wasserstein$p-{\rm Wasserstein}$ spaces Wp(Rn,dN)$ \mathcal {W}_p(\mathbb {R}^n, d_N)$ over Rn$\mathbb {R}^n$ equipped with a norm metric dN$d_N$. We show that, if the norm is smooth enough, then the Wasserstein space is isometrically rigid whenever p≠2$p \ne 2$.
Zoltán M. Balogh   +3 more
wiley   +1 more source

Unified Ray and Amplitude Tracing ODE Systems for the Eikonal and Transport Equations via Contact Geometry

open access: yesStudies in Applied Mathematics, Volume 157, Issue 3, September 2026.
ABSTRACT High‐frequency seismic wave descriptions are essential for fundamental geophysical applications, including earthquake hypocenter location, magnitude estimation, and traveltime–amplitude tomography. These descriptions rely on two coupled PDEs: the eikonal equation (governing traveltimes) and the transport equation (governing amplitudes ...
Ahmet Beyaz   +2 more
wiley   +1 more source

Refinements on higher order Weil–Oesterlé bounds via a Serre type argument

open access: yesBulletin of the London Mathematical Society, Volume 58, Issue 9, September 2026.
Abstract Weil's theorem gives the most standard bound on the maximum number of points Nq(g)$N_q(g)$ of a curve of genus g$g$ over a finite field Fq$\mathbb {F}_q$. This bound was improved by Ihara and Oesterlé for larger genus. A recent point of view allows one to recover these bounds by solving a sequence of semi‐definite programs, and the first two ...
Emmanuel Hallouin   +2 more
wiley   +1 more source

h$h$‐Function, Hilbert–Kunz density function and Frobenius–Poincaré function

open access: yesJournal of the London Mathematical Society, Volume 114, Issue 3, September 2026.
Abstract Given ideals I,J$I,J$ of a noetherian local ring (R,m)$(R, \mathfrak {m})$ such that I+J$I+J$ is m$\mathfrak {m}$‐primary and a finitely generated R$R$‐module M$M$, we associate an invariant of (M,R,I,J)$(M,R,I,J)$ called the h$h$‐function.
Cheng Meng, Alapan Mukhopadhyay
wiley   +1 more source

Testing for Conformity With Parametric Distributions Using Level Sets: From Univariate to Bivariate Applications

open access: yesStatistical Analysis and Data Mining: An ASA Data Science Journal, Volume 19, Issue 4, August 2026.
ABSTRACT Conformity of observed data with a postulated probability distribution is a fundamental problem of statistical modeling. Current tools for checking distributional conformity are often limited to univariate settings, with extensions to multivariate distributions facing challenges in interpretability and power.
Rasha Alsaadawi, Nitai D. Mukhopadhyay
wiley   +1 more source

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