Semi-invariant ξ⊥ -submersions from generalized quasi-Sasakian manifolds

Abstract

A structure on almost contact metric manifold is defined as a generalization of well-known cases: Sasakian, quasi-Sasakian, Kenmotsu, cosymplectic. We introduce semi-invariant ξ⊥ - submersions from a manifold with such structure onto a Riemannian manifold. We give examples, investigate the geometry of foliations defined from a Riemannian submersion, and find necessary and sufficient conditions for a semi-invariant ξ⊥ -submersion to be totally geodesic. ? 2017 Pushpa Publishing House, Allahabad, India.