English

Directed immersions for complex structures

Differential Geometry 2021-04-22 v3 Algebraic Geometry Algebraic Topology Complex Variables Symplectic Geometry

Abstract

We analyze the differential relation corresponding to integrability of almost complex structures, reformulated as a directed immersion relation by Demailly and Gaussier. Combining results of Clemente [3], we show that applying h-principle techniques yields the following statement: for an almost complex manifold with arbitrary metric (X,J,g)(X, J, g), and for ϵ>0\epsilon > 0, there exists a smooth function f:XRf : X \rightarrow \mathbb{R} and almost complex structure JJ' on XX such that JJ and JJ' are C0C^0-close on the graph of ff with respect to the extended metric on X×RX \times \mathbb{R}, and such that the Nijenhuis tensor of JJ' on the graph has pointwise sup norm less than CϵC\epsilon, where CC is a constant depending only on JJ and gg. This is an updated version of a previous preprint titled "Almost complex manifolds are (almost) complex".

Keywords

Cite

@article{arxiv.1903.10043,
  title  = {Directed immersions for complex structures},
  author = {Tobias Shin},
  journal= {arXiv preprint arXiv:1903.10043},
  year   = {2021}
}

Comments

This is an updated version of a previous preprint titled "Almost complex manifolds are (almost) complex"; most arguments are unchanged and the main theorem is restated correctly (that is, restated to what is actually proven by the arguments in the older version). Comments welcome

R2 v1 2026-06-23T08:17:33.903Z