English

Level sets of certain classes of $\alpha$-analytic functions

Complex Variables 2018-09-05 v4

Abstract

For an open set VCnV\subset\mathbb{C}^n, denote by Mα(V)\mathscr{M}_{\alpha}(V) the family of α\alpha-analytic functions that obey a boundary maximum modulus principle. We prove that, on a bounded domain ΩCn\Omega\subset \mathbb{C}^n, with continuous boundary (that in each variable separately allows a solution to the Dirichlet problem), a function fMα(Ωf1(0))f \in \mathscr{M}_{\alpha}(\Omega\setminus f^{-1}(0)) automatically satisfies fMα(Ω)f\in \mathscr{M}_{\alpha}(\Omega), if it is Cαj1C^{\alpha_j-1}-smooth, in the zjz_j variable, αZ+n\alpha\in \mathbb{Z}^n_+, up to the boundary. For a submanifold UCnU\subset \mathbb{C}^n, denote by Mα(U)\mathfrak{M}_{\alpha}(U) the set of functions locally approximable by α\alpha-analytic functions where each approximating member and its reciprocal (off the singularities) obey the boundary maximum modulus principle. We prove, that for a C3C^3-smooth hypersurface, Ω\Omega, a member of Mα(Ω)\mathfrak{M}_{\alpha}(\Omega), cannot have constant modulus near a point where the Levi form has a positive eigenvalue, unless it is there the trace of a polyanalytic function of a simple form.

Keywords

Cite

@article{arxiv.1612.06990,
  title  = {Level sets of certain classes of $\alpha$-analytic functions},
  author = {Abtin Daghighi and Frank Wikström},
  journal= {arXiv preprint arXiv:1612.06990},
  year   = {2018}
}

Comments

17 pages

R2 v1 2026-06-22T17:30:25.214Z