On two structural tensors of an acm-structure
Abstract
Almost contact metric structures on odd-dimensional manifolds are considered. The first group of the Cartan structural equations of an arbitrary almost contact metric structure written in an A-frame (i. e., in a frame adapted to this almost contact metric structure) is studied. It is proved that the fifth and sixth Kirichenko structural tensors of the almost contact metric structure vanish if and only if the structural contact form is closed.
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