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We analyze the classic problem of existence of Einstein metrics in a given conformal structure for the class of conformal structures inducedf Nurowski's construction by (oriented) (2,3,5) distributions. We characterize in two ways such…

Differential Geometry · Mathematics 2017-01-20 Katja Sagerschnig , Travis Willse

Almost paracontact Riemannian manifolds of the lowest dimension are studied, whose paracontact distributions are equipped with an almost paracomplex structure. These manifolds are constructed as a product of a real line and a 2-dimensional…

Differential Geometry · Mathematics 2023-09-06 Mancho Manev , Veselina Tavkova

This paper is a survey of results obtained by the authors on the geometry of connections with totally skew-symmetric torsion on the following manifolds: almost complex manifolds with Norden metric, almost contact manifolds with B-metric and…

Differential Geometry · Mathematics 2012-03-27 Mancho Manev , Dimitar Mekerov , Kostadin Gribachev

We define naturally Hermite-Lorentz metrics on almost-complex manifolds as special case of pseudo-Riemannian metrics compatible with the almost complex structure. We study their isometry groups.

Differential Geometry · Mathematics 2017-01-03 Ali Ben-Ahmed , Abdelghani Zeghib

Linear connections satisfying the Einstein metricity condition are important in the study of generalized Riemannian manifolds $(M,G=g+F)$, where the symmetric part $g$ of $G$ is a non-degenerate $(0,2)$-tensor, and $F$ is the skew-symmetric…

Differential Geometry · Mathematics 2025-08-12 Milan Zlatanović , Vladimir Rovenski

We introduce the notion of even Clifford structures on Riemannian manifolds, a framework generalizing almost Hermitian and quaternion-Hermitian geometries. We give the complete classification of manifolds carrying parallel even Clifford…

Differential Geometry · Mathematics 2019-01-08 Andrei Moroianu , Uwe Semmelmann

We study curvature invariants of a sub-Riemannian manifold (i.e., a manifold with a Riemannian metric on a non-holonomic distribution) related to mutual curvature of several pairwise orthogonal subspaces of the distribution, and prove…

Differential Geometry · Mathematics 2022-12-27 Vladimir Rovenski

We consider a pair of smooth manifolds, which are the counterparts in the even-dimensional and odd-dimensional cases. They are separately an almost complex manifold with Norden metric and an almost contact manifolds with B-metric,…

Differential Geometry · Mathematics 2015-05-06 Mancho Manev

The notion of relativistic observer is confronted with Naveira's classification of (pseudo-)Riemannian almost-product structures on space-time manifolds. Some physical properties and their geometrical counterparts are shortly discussed.

General Relativity and Quantum Cosmology · Physics 2014-12-04 Andrzej Borowiec , Aneta Wojnar

We introduce the notions of h-conformal slant submersions and almost h-conformal slant submersions from almost quaternionic Hermitian manifolds onto Riemannian manifolds as a generalization of Riemannian submersions, horizontally conformal…

Differential Geometry · Mathematics 2018-08-21 Kwang Soon Park , JeongHyeong Park

This proceeding presents a synthesis of recent results on the emergence of pseudo-Riemannian structures from twisted spectral triples within the almostcommutative framework. It provides a unified algebraic mechanism for addressing the…

Mathematical Physics · Physics 2026-05-12 Gaston Nieuviarts

In this note we give an alternative geometrical derivation of the results recently presented by Garcia-Godinez, Newman and Silva-Ortigoza in [1] on the class of all two-dimensional riemannian and lorentzian metrics from 2nd order ODEs which…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Emanuel Gallo

Recent work Bobienski-Nurowski on 5-dimensional Riemannian manifolds with an SO(3) structure prompts us to investigate which Lie groups admit such a geometry. The case in which the SO(3) structure admits a compatible connection with torsion…

Differential Geometry · Mathematics 2012-01-04 Anna Fino , Simon Chiossi

A 3-dimensional Riemannian manifold equipped with a tensor structure of type $(1,1)$, whose fourth power is the identity, is considered. This structure acts as an isometry with respect to the metric. A Riemannian almost product manifold…

Differential Geometry · Mathematics 2025-06-06 Iva Dokuzova

Following Geroch, Traschen, Mars and Senovilla, we consider Lorentzian manifolds with distributional curvature tensor. Such manifolds represent spacetimes of general relativity that possibly contain gravitational waves, shock waves, and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Philippe G. LeFloch , Cristinel Mardare

A 4-dimensional Riemannian manifold equipped with a circulant structure, which is an isometry with respect to the metric and its fourth power is the identity, is considered. The almost product manifold associated with the considered…

Differential Geometry · Mathematics 2017-03-24 Dobrinka Gribacheva , Dimitar Razpopov

In his book "Metric structures for Riemannian and non-Riemannian spaces", Gromov defined two properties of Riemannian manifolds, ellipticity and quasiregular ellipticity, and suggested that there may be a connection between the two. Since…

Differential Geometry · Mathematics 2025-12-05 Fedor Manin , Eden Prywes

Weak almost contact manifolds, i.e., the linear complex structure on the contact distribution is approximated by a nonsingular skew-symmetric tensor, defined by the author and R. Wolak (2022), allowed a new look at the theory of contact…

Differential Geometry · Mathematics 2024-05-03 Vladimir Rovenski

We study the relations between the projective and the almost conformally symplectic structures on a smooth even dimensional manifold. We describe these relations by a single almost conformally symplectic connection with totally trace--free…

Differential Geometry · Mathematics 2017-10-17 Jan Gregorovič

It is considered a differentiable manifold equipped with a pseudo-Riemannian metric and an almost contact 3-struc\-ture so that an almost contact metric structure and two almost contact B-metric structures are generated. There are…

Differential Geometry · Mathematics 2017-11-21 Mancho Manev