MathDB

Miklós Schweitzer 2007 Problem 5

Source:

March 3, 2017

Miklos Schweitzerreal analysisfunctioncollege contests

Problem Statement

Let

D=\{ (x,y) \mid x>0, y\neq 0\}

and let

u\in C^1(\overline {D})

be a bounded function that is harmonic on

D

and for which

u=0

on the

y

-axis. Prove that

u

is identically zero.
(translated by Miklós Maróti)