
doi: 10.1007/bf00046823
A. Bejancu defined CR submanifolds of differentiable manifolds with a (positive definite) Riemannian metric and almost Hermitian structure as a generalization of holomorphic submanifolds and totally real submanifolds. In this article, the notion of CR submanifold is extended to orientable Lorentz submanifolds of semi-Riemannian manifolds with an almost Hermitian structure. By a Lorentz submanifold we mean an n-dimensional submanifold embedded in an \((n+p)\)-dimensional semi-Riemannian manifold equipped with an indefinite metric, where the induced metric on the submanifold has Lorentzian signature (1,n-1). Definitions and theorems needed to extend the theory of CR submanifolds, contact CR submanifolds, and framed f-structures to the Lorentzian case are given. Many proofs are omitted as they are straight-forward generalizations but details of new results are presented. The primary new contribution is the study of CR submanifolds with a distribution D which is everywhere light- like, i.e. the metric restricted to D is degenerate. Several examples are presented and a discussion of how these notions relate to general relativity are included. For example, a four dimensional Lorentz CR manifold with a light-like distribution is related to the class of spacetimes representing null electromagnetic fields with the energy momentum tensor of a pure radiation field. Finally, a research problem to find the relation between Lorentzian geometry and pseudo conformal geometry is proposed.
Global differential geometry of Hermitian and Kählerian manifolds, framed f-structures, pseudo conformal geometry, Global differential geometry of Lorentz manifolds, manifolds with indefinite metrics, CR submanifolds, Electromagnetic fields in general relativity and gravitational theory, null electromagnetic fields, Lorentzian geometry, Applications of global differential geometry to the sciences, contact CR submanifolds, pure radiation field
Global differential geometry of Hermitian and Kählerian manifolds, framed f-structures, pseudo conformal geometry, Global differential geometry of Lorentz manifolds, manifolds with indefinite metrics, CR submanifolds, Electromagnetic fields in general relativity and gravitational theory, null electromagnetic fields, Lorentzian geometry, Applications of global differential geometry to the sciences, contact CR submanifolds, pure radiation field
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