关键词: Almost contact structure, contact structure, G₂-structure, foliation, integrability

Abstract: It is known that any hypersurface in an almost complex space admits an almost contact manifold[11, 14]. In this article we show that a hyperplane in an almost contact manifold has an almost complex structure. Along with this result, we explain how to determine when an almost contact structure induces a contact structure, followed by examples of a manifold with a closed G₂-structure.

Key words: Almost contact structure, contact structure, G₂-structure, foliation, integrability