Level Sets of Certain Subclasses of α-analytic Functions

Frank Wikström, Abtin Daghighi

Research output: Contribution to journalArticlepeer-review

Abstract

For an open set V subset of C-n, denote by M-alpha(V) the family of a-analytic functions that obey a boundary maximum modulus principle. We prove that, on a bounded "harmonically fat" domain Omega subset of C-n, a function f is an element of M-alpha (Omega\f(-1)(0)) automatically satisfies f is an element of M-alpha(Omega), if it is C alpha j-1-smooth in the z(j) variable, alpha is an element of Z(+)(n) up to the boundary. For a submanifold U subset of C-n, denote by M-alpha(U), the set of functions locally approximable by a-analytic functions where each approximating member and its reciprocal (off the singularities) obey the boundary maximum modulus principle. We prove, that for a C-3-smooth hypersurface, Omega, a member of 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. The result can be partially generalized to C-4-smooth submanifolds of higher codimension, at least near points with a Levi cone condition.
Translated title of the contributionNivåmängder för vissa klasser av α-analytiska funktioner
Original languageEnglish
Pages (from-to)281-298
JournalJournal of partial differential equations
Volume30
Issue number4
DOIs
Publication statusPublished - 2017

Subject classification (UKÄ)

  • Mathematical Analysis

Free keywords

  • polyanalytic functions
  • q -analytic functions
  • zero sets
  • level sets
  • α -analytic functions

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