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The paper is devoted to metric connections with parallel skew-symmetric torsion in Lorentzian signature. This is motivated by recent progress in the Riemannian signature and by possible applications to supergravity theories. We provide a…

Differential Geometry · Mathematics 2023-01-25 Igor Ernst , Anton S. Galaev

This article mainly aims to overview the recent efforts on developing algebraic geometry for an arbitrary compact almost complex manifold. We review the results obtained by the guiding philosophy that a statement for smooth maps between…

Differential Geometry · Mathematics 2020-10-09 Weiyi Zhang

We study the curvature of almost Hermitian manifolds and their special analogues via intrinsic torsion and representation theory. By deriving different forumlae for the skew-symmetric part of the star-Ricci curvature, we find that some of…

Differential Geometry · Mathematics 2007-05-23 Francisco Martin Cabrera , Andrew Swann

It is well-known that the class of piecewise smooth curves together with a smooth Riemannian metric induces a metric space structure on a manifold. However, little is known about the minimal regularity needed to analyze curves and…

Differential Geometry · Mathematics 2015-04-28 Annegret Y. Burtscher

We study the natural property of projectability of a torsion-free connection along a foliation on the underlying manifold, which leads to a projected torsion-free connection on a local leaf space, focusing on projectability of Levi-Civita…

Differential Geometry · Mathematics 2023-06-02 Andrzej Derdzinski , Kirollos Masood

In this paper the notion of the intrinsic geometry of an almost contact metric manifold is introduced. Description of some classes of spaces with almost contact metric structures in terms of the intrinsic geometry is given. A new type of…

Differential Geometry · Mathematics 2011-07-28 Sergey V. Galaev

We characterize general pseudo-harmonic morphisms from a Riemannian manifold to a Hermitian manifold as pseudo horizontally weakly conformal maps with an additional property. We study to what extent we can (locally) describe these…

Differential Geometry · Mathematics 2007-12-18 Radu Slobodeanu

We study point symmetries of the Robinson--Trautman equation. The cases of one- and two-dimensional algebras of infinitesimal symmetries are discussed in detail. The corresponding symmetry reductions of the equation are given. Higher…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Wlodzimierz Natorf , Jacek Tafel

In the present article the geometry of semi-Riemannian manifolds with nonholonomic constraints is studied. These manifolds can be considered as analogues to the sub-Riemannian manifolds, where the positively definite metric is substituted…

Differential Geometry · Mathematics 2009-01-13 Anna Korolko , Irina Markina

In the first part of the paper we investigate some geometric features of Moser-Trudinger inequalities on complete non-compact Riemannian manifolds. By exploring rearrangement arguments, isoperimetric estimates, and gluing local uniform…

Analysis of PDEs · Mathematics 2019-02-08 Alexandru Kristály

We discuss some basic concepts of semi-Riemannian geometry in low-regularity situations. In particular, we compare the settings of (linear) distributional geometry in the sense of L. Schwartz and nonlinear distributional geometry in the…

General Relativity and Quantum Cosmology · Physics 2011-06-21 Roland Steinbauer

A statistical manifold is a pseudo-Riemannian manifold endowed with a Codazzi structure. This structure plays an important role in Information Geometry and its related fields, e.g., a statistical model admits this structure with the…

Differential Geometry · Mathematics 2024-03-13 Kaito Kayo

We study the holonomy that is associated to a sub-Riemannian structure defined on the kernel of a global contact form. This includes the holonomy of Schouten's horizontal connection as well as of the adapted connection, both canonical…

Differential Geometry · Mathematics 2025-10-30 Anton S. Galaev , Thomas Leistner , Felipe Leitner

In this paper, we consider surfaces in 4--dimensional pseudo--Riemannian space--forms with index 2. First, we obtain some of geometrical properties of such surfaces considering their relative null space. Then, we get classifications of…

Differential Geometry · Mathematics 2019-10-30 Burcu Bektaş Demirci , Nurettin Cenk Turgay

We generalize the concept of sub-Riemannian geometry to infinite-dimensional manifolds modeled on convenient vector spaces. On a sub-Riemannian manifold $M$, the metric is defined only on a sub-bundle $\calH$ of the tangent bundle $TM$,…

Differential Geometry · Mathematics 2012-01-12 Erlend Grong , Irina Markina , Alexander Vasil'ev

The geometric approach to optimal transport and information theory has triggered the interpretation of probability densities as an infinite-dimensional Riemannian manifold. The most studied Riemannian structures are Otto's metric, yielding…

Analysis of PDEs · Mathematics 2018-07-20 Martin Bauer , Sarang Joshi , Klas Modin

We study Lorentzian manifolds $(M, g)$ of dimension $n\geq 4$, equipped with a maximally twisting shearfree null vector field $p_o$, for which the leaf space $S = M/\{\exp t p_o\}$ is a smooth manifold. If $n = 2k$, the quotient $S =…

Differential Geometry · Mathematics 2021-01-14 Dmitri V. Alekseevsky , Masoud Ganji , Gerd Schmalz , Andrea Spiro

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…

Differential Geometry · Mathematics 2017-03-08 Nabil L. Youssef , Ebtsam H. Taha

There are introduced and studied a pair of associated Schouten-van Kampen affine connections adapted to the paracontact distribution and an almost paracontact almost paracomplex Riemannian structure generated by the pair of associated…

Differential Geometry · Mathematics 2021-05-21 Hristo Manev , Mancho Manev

Almost paracontact almost paracomplex Riemannian manifolds of the lowest dimension 3 are considered. Such structures are constructed on a family of Lie groups and the obtained manifolds are studied. Curvature properties of these manifolds…

Differential Geometry · Mathematics 2021-05-21 Mancho Manev , Veselina Tavkova