English

Complete hyperbolic neighborhoods in almost-complex surfaces

Complex Variables 2007-05-23 v1 Symplectic Geometry

Abstract

We prove that each point in an almost-complex surface has a basis of complete hyperbolic neighborhoods. The problem is local, and therefore we can consider the case when our surface is R4{\bf R^4} with an arbitrary almost-complex structure JJ of class C1.αC^{1.\alpha}. Let CC be a non-singular JJ-complex curve passing through the origin. Our result cah be stated as follows: There exists a basis {Uj}\{U_j\} of neighborhoods of zero in R4{\bf R^4}, such that (Uj,J)(U_j,J) are complete hyperbolic in the sence of Kobayashi, moreover (UjC,J)(U_j\setminus C,J) are complete hyperbolic as well. The fact that this result remains true for any almost-complex structure is somewhat suprising. Really, given any germ of a non-singular real surface C0C\ni 0 in R4{\bf R^4}, one can easily construct an almost-complex structure JJ in a neighborhood of zero, such that CC becomes a JJ-complex curve. Typical corollary is the following: Let Mω,5l{\cal M}_{\omega, 5l} be the Banach manifold consisting of pairs (J,{Dj}j=15)(J,\{D_j\}_{j=1}^5), where JJ is any almost-complex structure on CP2{\bf CP^2} tamed by the Fubini-Studi form ω\omega and {Dj}j=15\{D_j\}_{j=1}^5 the union of five JJ-complex lines in CP2{\bf CP^2} in general position. The set Hω,5l{\cal H}_{\omega, 5l} consisting of (J,{Dj}j=15)(J, \{D_j\}_{j=1}^5) with Y=(CP2j=15Dj,J)Y=({\bf CP^2}\setminus \bigcup_{j=1}^5 D_j,J) hyperbolically imbedded into (CP2,J)({\bf CP^2}, J) is an open nonempty subset of Mω,5l{\cal M}{\omega, 5l}.

Keywords

Cite

@article{arxiv.math/0002156,
  title  = {Complete hyperbolic neighborhoods in almost-complex surfaces},
  author = {R. Debalme and S. Ivashkovich},
  journal= {arXiv preprint arXiv:math/0002156},
  year   = {2007}
}

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12 pages