Results 31 to 40 of about 252 (77)
Cosmological perfect-fluids in f(R) gravity [PDF]
, 2018 We show that an n-dimensional generalized Robertson-Walker (GRW) space-time with divergence-free conformal curvature tensor exhibits a perfect fluid stress-energy tensor for any f(R) gravity model.
Capozziello, Salvatore +2 more
core +2 more sources
CERTAIN RESULTS OF RICCI-YAMABE SOLITONS ON $(LCS)_N$-MANIFOLDS [PDF]
, 2022 The goal of this paper is to characterize Lorentzian concircular structure manifolds (briefly, $(LCS)_n$-manifolds) admitting Ricci-Yamabe solitons.
Singh, Jay Prakash +1 more
core +1 more source
Almostη-Ricci and almostη-Yamabe solitons with torse-forming potential vector field
Quaestiones Mathematicae, 2020 We provide properties of almost $η$-Ricci and almost $η$-Yamabe solitons on submanifolds isometrically immersed into a Riemannian manifold $\left(\widetilde{M},\widetilde{g} \right)$ whose potential vector field is the tangential component of a torse-forming vector field on $\widetilde{M}$, treating also the case of a minimal or pseudo quasi-umbilical ...
Blaga, Adara M., Özgür, Cihan
openaire +4 more sources
, 2023 Almost contact complex Riemannian manifolds, known also as almost contact B-metric manifolds, are in principle equipped with a pair of mutually associated pseudo-Riemannian metrics.
Manev, Mancho
core +1 more source
On Riemannian manifolds endowed with a locally conformal cosymplectic structure
International Journal of Mathematics and Mathematical Sciences, Volume 2005, Issue 21, Page 3471-3478, 2005., 2005 We deal with a locally conformal cosymplectic manifold M(φ, Ω, ξ, η, g) admitting a conformal contact quasi‐torse‐forming vector field T. The presymplectic 2‐form Ω is a locally conformal cosymplectic 2‐form. It is shown that T is a 3‐exterior concurrent vector field. Infinitesimal transformations of the Lie algebra of ∧M are investigated.
Ion Mihai, Radu Rosca, Valentin Ghişoiu
wiley +1 more source
On a class of even‐dimensional manifolds structured by an affine connection
International Journal of Mathematics and Mathematical Sciences, Volume 29, Issue 11, Page 681-686, 2002., 2002 We deal with a 2m‐dimensional Riemannian manifold (M, g) structured by an affine connection and a vector field 𝒯, defining a 𝒯‐parallel connection. It is proved that 𝒯 is both a torse forming vector field and an exterior concurrent vector field. Properties of the curvature 2‐forms are established.
I. Mihai, A. Oiagă, R. Rosca
wiley +1 more source
On a class of exact locally conformal cosymlectic manifolds
International Journal of Mathematics and Mathematical Sciences, Volume 19, Issue 2, Page 267-278, 1996., 1994 An almost cosymplectic manifold M is a (2m + 1)‐dimensional oriented Riemannian manifold endowed with a 2‐form Ω of rank 2m, a 1‐form η such that Ωm Λ η ≠ 0 and a vector field ξ satisfying iξΩ = 0 and η(ξ) = 1. Particular cases were considered in [3] and [6].
I. Mihai, L. Verstraelen, R. Rosca
wiley +1 more source
Ricci‐Bourguignon Solitons With Certain Applications to Relativity
Journal of Mathematics, Volume 2025, Issue 1, 2025.This article concerns with the investigation of Ricci‐Bourguignon solitons and gradient Ricci‐Bourguignon solitons in perfect fluid space‐times and generalised Robertson–Walker space‐times. First, we deduce the criterion for which the Ricci‐Bourguignon soliton in a perfect fluid space‐time is steady, expanding or shrinking. Then, we establish that if a
Krishnendu De +4 more
wiley +1 more source
η-Ricci solitons in (ε)-almost paracontact metric manifolds [PDF]
, 2018 The object of this paper is to study η -Ricci solitons on ( ε ) -almost paracontact metric manifolds. We investigate η -Ricci solitons in the case when its potential vector field is exactly the characteristic vector field ξ of the ( ε ) -almost ...
Adara Monica Blaga +3 more
core +2 more sources
Geometric Classifications of Perfect Fluid Space‐Time Admit Conformal Ricci‐Bourguignon Solitons
Journal of Mathematics, Volume 2024, Issue 1, 2024.This paper is dedicated to the study of the geometric composition of a perfect fluid space‐time with a conformal Ricci‐Bourguignon soliton, which is the extended version of the soliton to the Ricci‐Bourguignon flow. Here, we have delineated the conditions for conformal Ricci‐Bourguignon soliton to be expanding, steady, or shrinking.
Noura Alhouiti +6 more
wiley +1 more source