Level Sets of Certain Subclasses of α-Analytic Functions

作     者：DAGHIGHI Abtin WIKSTROM Frank 

作者机构：Mid Sweden University Holmgatan 10 SE-851 70 Sundsvall Sweden Center for Mathematical Sciences Lund University Box 118 SE-22100 Lund Sweden 

出 版 物：《Journal of Partial Differential Equations》 (偏微分方程（英文版）)

年 卷 期：2017年第30卷第4期

页      面：281-298页

核心收录：

学科分类：07[理学] 08[工学] 070104[理学-应用数学] 0835[工学-软件工程] 0701[理学-数学] 081202[工学-计算机软件与理论] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

主　　题：Polyanalytic functions q-analytic functions zero sets level sets a-analytic functions. 

摘      要：For an open set V C Cn, denote by Mα （V） the family of α-analytic functions that obey a boundary maximum modulus principle. We prove that, on a bounded ＂harmonically fat＂ domain Ω C Cn, a function f ∈M a（Ω／f-1（0）） automatically sat- isfies f ∈M a（Ω）, if it is Caj-1smooth in the z/variable, α ∈ Zn＋ up to the boundary. For a submanifold U C Cn, denote by ma（U）, the set of functions locally approximable by α-analytic functions where each approximating member and its reciprocal （off the singularities） obey the boundary maximum modulus principle. We prove, that for a C3-smooth hypersurface, Ω, a member of ma （Ω）, 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 C4-smooth submanifolds of higher codimension, at least near points with a Levi cone condition.