Abstract
We give an improvement of the result that if $hP\ge0$ on $\R^n$, where $h$ is a harmonic function and $P$ a non-trivial harmonic polynomial, then $h$ is proportional to $P$.
Citation
D. H. Armitage. "The Determination of a Harmonic Function by Its Sign." Real Anal. Exchange 33 (2) 275 - 278, 2007/2008.
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