90 citations · 98 across the 3 of their papers we have counts for
3 papers
math.DG2015★ 8 cited
On the (1+3) threading of spacetime with respect to an arbitrary timelike vector field
Aurel Bejancu, Constantin Călin
We develop a new approach on the (1+3) threading of spacetime with respect to a congruence of curves defined by an arbitrary timelike vector field. The study is based on s…
math.DG2010★ 90 cited
From the Eisenhart problem to Ricci solitons in -Kenmotsu manifolds
Constantin Călin, Mircea Crasmareanu
The Eisenhart problem of finding parallel tensors is solved for the symmetric case in the regular -Kenmotsu framework. On this way, the Olszack-Rosca example of Einstein manifol…
math.DG2010
Semi-invariant -submanifolds of generalized quasi-Sasakian manifolds
Constantin Călin, Mircea Crâşmareanu, Marian Ioan Munteanu +1
A structure on an almost contact metric manifold is defined as a generalization of well-known cases: Sasakian, quasi-Sasakian, Kenmotsu and cosymplectic. Then we consider a semi-in…