Results 61 to 70 of about 892 (193)

Constant curvature models in sub-Riemannian geometry

Journal of Geometry and Physics, 2019
The second version reflected comments from the reviewing process. Introduction and parts of exposition are extended, some proofs made more precise.
Dmitri V. Alekseevsky, Alexandr Medvedev, Alexandr Medvedev, Jan Slovák   +3 more
openaire   +3 more sources

Asymptotics of quantum 6j$6j$‐symbols and generalized hyperbolic tetrahedra

Journal of Topology, Volume 18, Issue 3, September 2025.
Abstract We establish the geometry behind the quantum 6j$6j$‐symbols under only the admissibility conditions as in the definition of the Turaev–Viro invariants of 3‐manifolds. As a classification, we show that the 6‐tuples in the quantum 6j$6j$‐symbols give in a precise way to the dihedral angles of (1) a spherical tetrahedron, (2) a generalized ...
Giulio Belletti, Tian Yang
wiley   +1 more source

BiLipschitz Decomposition of Lipschitz Maps between Carnot Groups

Analysis and Geometry in Metric Spaces, 2015
Let f : G → H be a Lipschitz map between two Carnot groups. We show that if B is a ball of G, then there exists a subset Z ⊂ B, whose image in H under f has small Hausdorff content, such that B\Z can be decomposed into a controlled number of pieces, the ...
Li Sean
doaj   +1 more source

Legendrian non‐isotopic unit conormal bundles in high dimensions

Journal of Topology, Volume 18, Issue 3, September 2025.
Abstract For any compact connected submanifold K$K$ of Rn$\mathbb {R}^n$, let ΛK$\Lambda _K$ denote its unit conormal bundle, which is a Legendrian submanifold of the unit cotangent bundle of Rn$\mathbb {R}^n$. In this paper, we give examples of pairs (K0,K1)$(K_0,K_1)$ of compact connected submanifolds of Rn$\mathbb {R}^n$ such that ΛK0$\Lambda _{K_0}$
Yukihiro Okamoto
wiley   +1 more source

Uniform Gaussian Bounds for Subelliptic Heat Kernels and an Application to the Total Variation Flow of Graphs over Carnot Groups

Analysis and Geometry in Metric Spaces, 2013
In this paper we study heat kernels associated with a Carnot group G, endowed with a family of collapsing left-invariant Riemannian metrics σε which converge in the Gromov- Hausdorff sense to a sub-Riemannian structure on G as ε→ 0.
Capogna Luca, Citti Giovanna, Manfredini Maria   +2 more
doaj   +1 more source

Cross‐Dataset Evaluation of Dementia Longitudinal Progression Prediction Models

Human Brain Mapping, Volume 46, Issue 11, 01 August 2025.
We introduced a simplified variant of FROG, the winning algorithm of the TADPOLE challenge, for predicting dementia progression using multimodal longitudinal data. Combining the longitudinal‐to‐cross‐sectional (L2C) transformation with a multi‐task feedforward neural network (FNN), L2C‐FNN demonstrated superior generalizability when trained on ADNI and
Chen Zhang, Lijun An, Naren Wulan, Kim‐Ngan Nguyen, Csaba Orban, Pansheng Chen, Christopher Chen, Juan Helen Zhou, Keli Liu, B. T. Thomas Yeo, Alzheimer's Disease Neuroimaging Initiative and Australian Imaging Biomarkers and Lifestyle Study of Aging   +10 more
wiley   +1 more source

Left-invariant paracontact metric structure on a group Sol

Дифференциальная геометрия многообразий фигур
Among Thurston's famous list of eight three-dimensional geometries is the geometry of the manifold Sol. The variety Sol is a connected simply connected Lie group of real matrices of a special form.
M. V. Sorokina, O. P. Surina
doaj   +1 more source

Structured Nuclear Norm Matrix Completion: Guaranteeing Exact Recovery via Block‐Column Scaling

Numerical Linear Algebra with Applications, Volume 32, Issue 4, August 2025.
ABSTRACT The goal of low‐rank matrix completion is to minimize the rank of a matrix while adhering to the constraint that known (non‐missing) elements are fixed in the approximation. Minimizing rank is a difficult, non‐convex, NP‐hard problem, often addressed by substituting rank with the nuclear norm to achieve a convex relaxation.
Konstantin Usevich, Jonathan Gillard, Philippe Dreesen, Ivan Markovsky   +3 more
wiley   +1 more source

Nonexistence results of nonnegative solutions of elliptic equations and systems on the Heisenberg group

AIMS Mathematics
This paper establishes sharp nonexistence criteria for nonnegative solutions to a class of quasilinear elliptic inequalities and divergence-type systems in the subelliptic framework of the Heisenberg group $ H^n $.
Wei Shi
doaj   +1 more source

Connections in sub-Riemannian geometry of parallelizable distributions [PDF]

International Journal of Geometric Methods in Modern Physics, 2017
The notion of a parallelizable distribution has been introduced and investigated. A non-integrable parallelizable distribution carries a natural sub-Riemannian structure. The geometry of this structure has been studied from the bi-viewpoint of absolute parallelism geometry and sub-Riemannian geometry.
Ebtsam H. Taha, Nabil L. Youssef
openaire   +3 more sources