Generalized Robertson–Walker spacetimes extend the notion of Robertson–Walker
spacetimes, by allowing for spatial non-homogeneity. A survey is presented, with main focus …

Page 1 Differential Geometry. Lightlike Submanifolds Page 2 Page 3 Frontiers in Mathematics
Advisory Editorial Board Leonid Bunimovich (Georgia Institute of Technology, Atlanta) Benoît …

Inspired by a result of Boyer and Galicki, we prove that a complete K-contact gradient soliton
is compact Einstein and Sasakian. For the non-gradient case we show that the soliton vector …

This is a first textbook that is entirely focused on the up-to-date developments of null curves
with their applications to science and engineering. It fills an important gap in a second-level …

This paper deals with the study of perfect fluid spacetimes. It is proven that a perfect fluid
spacetime is Ricci recurrent if and only if the velocity vector field of perfect fluid spacetime is …

In this paper, we consider*-Ricci soliton in the frame-work of Kenmotsu manifolds. First, we
prove that if (M, g) is a Kenmotsu manifold and g is a*-Ricci soliton, then soliton constant λ is …

The focus of this paper is to characterize the Lorentzian manifolds equipped with a semi-
symmetric non-metric ρ-connection [briefly,(M,∇ ̃)]. The conditions for a Lorentzian manifold …

In this article, we investigate perfect fluid spacetimes equipped with concircular vector field.
At first, in a perfect fluid spacetime admitting concircular vector field, we prove that the …

In this paper, we study para-Sasakian manifold (M, g) whose metric g is an η-Ricci soliton (g,
V) and almost η-Ricci soliton. We prove that, if g is an η-Ricci soliton, then either M is …

This paper characterizes the Lorentzian manifolds endowed with a semi-symmetric non-
metric ρ-connection (briefly, ssnmρc). First, the existence of semi-symmetric non-metric …