Results 131 to 140 of about 87,863 (252)

A generalization of contact metric manifolds [PDF]

arXiv, 2013
We give a characterization of a contact metric manifold as a special almost contact metric manifold and discuss an almost contact metric manifold which is {a} natural generalization of the contact metric manifolds introduced by Y. Tashiro.
arxiv  

Learning group invariant Calabi–Yau metrics by fundamental domain projections

Machine Learning: Science and Technology
We present new invariant machine learning models that approximate the Ricci-flat metric on Calabi–Yau (CY) manifolds with discrete symmetries. We accomplish this by combining state of the art models for predicting such metrics, based on the so-called φ ...
Yacoub Hendi, Magdalena Larfors, Moritz Walden   +2 more
doaj   +1 more source

Weakly holomorphic homogeneous regular manifolds [PDF]

arXiv
We introduce a class of complex manifolds which we call weakly holomorphic homogeneous regular manifolds (wHHR) manifolds. As the name suggests, this class contains the so-called holomorphic homogeneous regular manifolds but also other classes of complex manifolds such as two dimensional finite type domains and simply connected K\"ahler manifolds with ...
arxiv  

A Ricci flat pseudo-Riemannian metric on the tangent bundle of a Riemannian manifold [PDF]

, 2001
Neculai Papaghiuc
openalex   +1 more source

Three-dimensional Riemannian manifolds associated with locally conformal Riemannian product manifolds [PDF]

arXiv
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 associated with such a manifold is also studied.
arxiv  

On a type of spacetime [PDF]

Mathematica Moravica, 2014
The object of the present paper is to study a special type of spacetime. It is proved that in a conformally flat (W RS)4 spacetime with non-zero scalar curvature the vector field p defined by ɡ(X, p) = E(X) is irrotational and the integral curves of the ...
Mallick Sahanous, Chand De Uday
doaj  

Non-zero degree maps between closed orientable three-manifolds [PDF]

arXiv, 2005
This paper adresses the following problem: Given a closed orientable three-manifold M, are there at most finitely many closed orientable three-manifolds 1-dominated by M? We solve this question for the class of closed orientable graph manifolds. More presisely the main result of this paper asserts that any closed orientable graph manifold 1-dominates ...
arxiv  

On the Optimal Control of Impulsive Hybrid Systems On Riemannian Manifolds [PDF]

arXiv, 2012
This paper provides a geometrical derivation of the Hybrid Minimum Principle (HMP) for autonomous impulsive hybrid systems on Riemannian manifolds, i.e. systems where the manifold valued component of the hybrid state trajectory may have a jump discontinuity when the discrete component changes value.
arxiv  

Essential constants for spatially homogeneous Ricci-flat manifolds of dimension 4+1 [PDF]

, 2004
T. Christodoulakis, Sigbjørn Hervik, G. Papadopoulos   +2 more
openalex   +1 more source

Generalized Isotropic Berwald Manifolds [PDF]

arXiv, 2013
In this paper, we construct a new class of Finsler manifolds called generalized isotropic Berwald manifolds which is an extension of the class of isotropic Berwald manifolds. We prove that every generalized isotropic Berwald manifold is a generalized Douglas-Weyl manifold. On a compact generalized isotropic Berwald manifold, we show that the notions of
arxiv