Differential Geometry of Manifolds

2023 №54(1)

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On connections with torsion on nonholonomic para-Kenmotsu manifolds

DOI
10.5922/0321-4796-2023-54-1-6
Pages
49-63

Abstract

The concept of a nonholonomic para-Kenmotsu manifold is intro­duced. A nonholonomic para-Kenmotsu manifold is a natural generaliza­tion of a para-Kenmotsu manifold; the distribution of a nonholonomic para-Kenmotsu manifold does not need to be involutive. Properly nonho­lonomic para-Kenmotsu manifolds are singled out, these are nonho­lono­mic para-Kenmotsu manifolds with non-involutive distribution. On an al­most (para-)contact metric manifold, we introduce a metric connec­tion with torsion, which is called a connection of Levi-Civita type in this pa­per. In the case of a nonholonomic para-Kenmotsu manifold, such a con­nection has a simpler structure than the Levi-Civita connection, and in so­me cases it turns out to be preferable from an applied point of view. A Le­vi-Civita type connection coincides with a Levi-Civita connec­tion if and only if a nonholonomic para-Kenmotsu manifold reduc­es to a para-Ken­motsu manifold. It is proved that a proper nonholonomic para-Ken­motsu manifold cannot carry the structure of an Einstein mani­fold with respect to a connection of the Levi-Civita type.

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