CR manifold

From Wikipedia, the free encyclopedia

In mathematics, a CR manifold is a differentiable manifold M with a preferred complex distribution L, or in other words a subbundle of the complexified tangent bundle

\mathbb{C}TM = TM\otimes\mathbb{C}.

It is required to satisfy

  • [L,L]\subseteq L
  • L\cap\bar{L}=\{0\}


The canonical example of a CR manifold is the real 2n + 1 sphere as a submanifold of \mathbb{C}^{n+1}. The bundle L described above is given by

L = \mathbb{C}TS^{2n+1} \cap T^{1,0}\mathbb{C}^{n+1}

where T^{1,0}\mathbb{C}^{n+1} is the bundle of holomorphic vectors. The real form of this is given by P=\Re (L\oplus \bar{L}), the bundle given at a point p\in S^{2n+1} concretely in terms of the complex structure, I, on \mathbb{C}^{n+1} by

P_p = \{ X\in T_pS^{2n+1} : IX \in T_pS^{2n+1}\subset T_p\mathbb{C}^{n+1}\},

and the almost complex structure on P is just the restriction of I.