Results 81 to 90 of about 82,161 (203)

Contact Semi-Riemannian Structures in CR Geometry: Some Aspects

Axioms, 2019
There is one-to-one correspondence between contact semi-Riemannian structures ( η , ξ , φ , g ) and non-degenerate almost CR structures ( H , ϑ , J ) .
Domenico Perrone
doaj   +1 more source

In‐and‐Out: Algorithmic Diffusion for Sampling Convex Bodies

Random Structures &Algorithms, Volume 68, Issue 3, May 2026.
ABSTRACT We present a new random walk for uniformly sampling high‐dimensional convex bodies. It achieves state‐of‐the‐art runtime complexity with stronger guarantees on the output than previously known, namely in Rényi divergence (which implies TV, 𝒲2, KL, χ2$$ {\chi}^2 $$).
Yunbum Kook, Santosh S. Vempala, Matthew S. Zhang   +2 more
wiley   +1 more source

Kuramoto Model on Sierpinski Gasket I: Harmonic Maps

Studies in Applied Mathematics, Volume 156, Issue 5, May 2026.
ABSTRACT Motivated by the study of attractors in the Kuramoto model (KM) on graphs, approximating the Sierpinski gasket (SG), we revisit the problem of harmonic maps (HMs) from SG to the circle, first considered by Strichartz. We provide a geometric proof of Strichartz's theorem, which states that for a prescribed degree and suitable boundary ...
Georgi S. Medvedev, Matthew S. Mizuhara
wiley   +1 more source

Lorentzian homogeneous structures with indecomposable holonomy

Journal of the London Mathematical Society, Volume 113, Issue 5, May 2026.
Abstract For a Lorentzian homogeneous space, we study how algebraic conditions on the isotropy group affect the geometry and curvature of the homogeneous space. More specifically, we prove that a Lorentzian locally homogeneous space is locally isometric to a plane wave if it admits an Ambrose–Singer connection with indecomposable, non‐irreducible ...
Steven Greenwood, Thomas Leistner
wiley   +1 more source

Commutative curvature operators over four-dimensional generalized symmetric

Sahand Communications in Mathematical Analysis, 2014
Commutative properties of four-dimensional generalized symmetric pseudo-Riemannian manifolds were considered. Specially, in this paper, we studied Skew-Tsankov and Jacobi-Tsankov conditions in 4-dimensional pseudo-Riemannian generalized symmetric ...
Ali Haji-Badali, Masoud Dehghan, Fereshteh Nourmohammadi   +2 more
doaj  

The Morse Index of Sacks–Uhlenbeck α-Harmonic Maps for Riemannian Manifolds

Journal of Mathematics
In this paper, first we prove a nonexistence theorem for α-harmonic mappings between Riemannian manifolds. Second, the instability of nonconstant α-harmonic maps is studied with regard to the Ricci curvature criterion of their codomain. Then, we estimate
Amir Shahnavaz, Nader Kouhestani, Seyed Mehdi Kazemi Torbaghan   +2 more
doaj   +1 more source

Property of the curvatures of integrable poly-Norden manifolds and their submanifolds [PDF]

Journal of Mahani Mathematical Research
In the present paper, almost poly-Norden and locally almost poly-Norden manifolds are investigated. Ricci tensor and Riemannian curvature of integrable poly-Norden manifolds are studied. Geometric properties of   submanifolds of these types of  manifolds
Masoumeh Tofighi, Mohammad Bagher Kazemi Balgeshir   +1 more
doaj   +1 more source

Two-Root Riemannian Manifolds

Mediterranean Journal of Mathematics, 2023
Osserman manifolds are a generalization of locally two-point homogeneous spaces. We introduce $k$-root manifolds in which the reduced Jacobi operator has exactly $k$ eigenvalues. We investigate one-root and two-root manifolds as another generalization of locally two-point homogeneous spaces. We prove that there is no two-root Riemannian manifold of odd
openaire   +2 more sources

An Equivalence Theorem and A Sequential Algorithm for A-Optimal Experimental Designs on Manifolds

Axioms
Selecting input data points in the context of high-dimensional, nonlinear, and complex data in Riemannian space is challenging. While optimal experimental design theory is well-established in Euclidean space, its extension to Riemannian manifolds remains
Jingwen Zhang, Yaping Wang
doaj   +1 more source

Stochastic Approximation on Riemannian Manifolds [PDF]

Applied Mathematics & Optimization, 2019
The standard theory of stochastic approximation (SA) is extended to the case when the constraint set is a Riemannian manifold. Specifically, the standard ODE method for analyzing SA schemes is extended to iterations constrained to stay on a manifold using a retraction mapping. In addition, for submanifolds of a Euclidean space, a framework is developed
openaire   +3 more sources