Semi-invariant semi-Riemannian submersions

Abstract

In this paper, we introduce semi-invariant semi-Riemannian submersions from para-Kähler manifolds onto semi-Riemannian manifolds. Wegive some examples, investigate the geometry of foliations that arise fromthe de…nition of a semi-Riemannian submersion and check the harmonicity ofsuch submersions. We also find necessary and su¢ cient conditions for a semiinvariant semi-Riemannian submersion to be totally geodesic. Moreover, weobtain curvature relations between the base manifold and the total manifold