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We consider here the $3$-sphere $\mathbf S^3$ seen as the boundary at infinity of the complex hyperbolic plane $\mathbf{H}^2_{\mathbf C}$. It comes equipped with a contact structure and two classes of special curves. First $\mathbf…

Geometric Topology · Mathematics 2022-05-19 Elisha Falbel , Antonin Guilloux , Pierre Will

We study the influence of the existence of totally geodesic null hypersurface on the properties of a Lorentzian manifold. By coupling the rigging technique with the existence of a null foliation we prove the existence of a Riemann flow…

Differential Geometry · Mathematics 2025-03-05 Manuel Gutiérrez , Raymond A. Hounnonkpe

We introduce veering branched surfaces as a dual way of studying veering triangulations. We then discuss some surgical operations on veering branched surfaces. Using these, we provide explicit constructions of some veering branched surfaces…

Geometric Topology · Mathematics 2024-01-05 Chi Cheuk Tsang

We investigate the rudiments of Riemannian geometry on orbit spaces $M/G$ for isometric proper actions of Lie groups on Riemannian manifolds. Minimal geodesic arcs are length minimising curves in the metric space $M/G$ and they can hit…

Differential Geometry · Mathematics 2007-05-23 Dmitry Alekseevsky , Andreas Kriegl , Mark Losik , Peter W. Michor

This paper introduces the geodesics of triangulated image object shapes. Both rectilinear and curvilinear triangulations of shapes are considered. The triangulation of image object shapes leads to collections of what are known as nerve…

Computational Geometry · Computer Science 2017-08-25 M. Z. Ahmad , J. F. Peters

We establish a twistor correspondence between a cuspidal cubic curve in a complex projective plane, and a co-calibrated homogeneous $G_2$ structure on the seven--dimensional parameter space of such cubics. Imposing the Riemannian reality…

Differential Geometry · Mathematics 2012-01-27 Boris Doubrov , Maciej Dunajski

We investigate the problem of learning to generate 3D parametric surface representations for novel object instances, as seen from one or more views. Previous work on learning shape reconstruction from multiple views uses discrete…

Computer Vision and Pattern Recognition · Computer Science 2020-08-19 Jiahui Lei , Srinath Sridhar , Paul Guerrero , Minhyuk Sung , Niloy Mitra , Leonidas J. Guibas

The isometric immersion of two-dimensional Riemannian manifolds or surfaces in the three-dimensional Euclidean space is a fundamental problem in differential geometry. When the Gauss curvature is negative, the isometric immersion problem is…

Differential Geometry · Mathematics 2016-06-27 Wentao Cao , Feimin Huang , Dehua Wang

With the developments of the last decade on complete constant mean curvature 1 (CMC 1) surfaces in the hyperbolic 3-space $H^3$, many examples of such surfaces are now known. However, most of the known examples have regular ends. (An end is…

Differential Geometry · Mathematics 2008-05-27 Wayne Rossman , Masaaki Umehara , Kotaro Yamada

We investigate the universal Severi variety of rational curves on K3 surfaces, which parametrises irreducible rational curves in a fixed class on varying K3 surfaces of fixed genus. We investigate the conjecuted irreducibility of this space…

Algebraic Geometry · Mathematics 2014-07-23 Michael Kemeny

We study a data-driven sub-Riemannian (SR) curve optimization model for connecting local orientations in orientation lifts of images. Our model lives on the projective line bundle $\mathbb{R}^{2} \times P^{1}$, with $P^{1}=S^{1}/_{\sim}$…

Optimization and Control · Mathematics 2017-04-14 E. J. Bekkers , R. Duits , A. Mashtakov , Yu. Sachkov

In this paper we reconsider the sub-Riemannian cortical model of image completion introduced by Sarti and Citti in 2003. This model combines two mechanisms, the sub-Riemannian diffusion and the concentration, giving rise to a diffusion…

Analysis of PDEs · Mathematics 2015-04-16 Giovanna Citti , Benedetta Franceschiello , Gonzalo Sanguinetti , Alessandro Sarti

A translation surface in the three-dimensional sphere $\mathbb{S}^3$ is a surface generated by the quaternionic product of two curves, called generating curves. In this paper, we present rigidity results for such surfaces. We introduce an…

Differential Geometry · Mathematics 2025-07-30 Tarcios Andrey Ferreira , João Paulo dos Santos

We find the minimal value of the length in de Sitter space of closed space-like curves with non-vanishing non-space-like geodesic curvature vector. These curves are in correspondence with closed almost-regular canal surfaces, and their…

Differential Geometry · Mathematics 2011-08-12 Rémi Langevin , Gil Solanes

In this paper we study horizontal curvatures for surfaces embedded in three-dimensional contact sub-Riemannian Lie groups. Using a Riemannian approximation scheme, we derive explicit formulas for horizontal Gauss curvature, horizontal mean…

Differential Geometry · Mathematics 2026-03-10 Elia Bubani , Andrea Pinamonti , Ioannis D. Platis , Dimitrios Tsolis

We introduce variational approximations for curve evolutions in two-dimensional Riemannian manifolds that are conformally flat, i.e.\ conformally equivalent to the Euclidean space. Examples include the hyperbolic plane, the hyperbolic disk,…

Numerical Analysis · Mathematics 2020-07-15 John W. Barrett , Harald Garcke , Robert Nürnberg

We consider surfaces of class $C^1$ in the $3$-dimensional sub-Riemannian Heisenberg group ${\mathbb H}^1$. Assuming the surface is area-stationary, i.e., a critical point of the sub-Riemannian perimeter under compactly supported…

Differential Geometry · Mathematics 2015-08-21 Matteo Galli , Manuel Ritoré

We introduce a new formulation of the so-called topological recursion, that is defined globally on a compact Riemann surface. We prove that it is equivalent to the generalized recursion for spectral curves with arbitrary ramification. Using…

Mathematical Physics · Physics 2013-03-07 Vincent Bouchard , Bertrand Eynard

Motivated to study the geometry of the exotic spheres constructed in [5], we derive a necessary condition for non-negative sectional curvature in certain total spaces of Riemannian submersions with totally geodesic fibers. In particular, we…

Differential Geometry · Mathematics 2012-06-11 Llohann Sperança

We present a neuro-mathematical model for geometrical optical illusions (GOIs), a class of illusory phenomena that consists in a mismatch of geometrical properties of the visual stimulus and its associated percept. They take place in the…

Neurons and Cognition · Quantitative Biology 2020-02-20 Benedetta Franceschiello , Alexey Mashtakov , Giovanna Citti , Alessandro Sarti