Further Aspects of the Fueter Mapping Theorem

Abstract

In this paper we first show that for $n$ being even the images of the Fueter mapping, as monogenic functions, like for the odd $n$ cases proved through computation on the pointwise differential operator, are also of the axial type (the Axial Form Theorem). Due to a recent result of B. Dong, K. I. Kou, T. Qian, I. Sabadini (2016), we know that the Fueter mapping is surjective on the set of all left- and right-monogenic functions of the axial type in axial domains (the Surjectivity Theorem). The second part results of this paper address the action of the Fueter mapping on the monomials $f^{(l)}_0(z)=z^l, l=0, \pm 1, \pm 2,...,$ in one complex variable. In generalizing the Fueter and the Sce theorems to the even dimensions $n,$ Qian used the following mapping $τ$ (applicable for odd dimensions as well): $$τ(f^{(-k)}_0)=\mathcal{F}^{-1}((-2π|\cdot |)^{n-1}\mathcal{F}({\vec{f_0^{(-k)}}})), \ \ \ τ(f^{(n-2+k)}_0)=I(τ(f^{(-k)}_0)), $$ where $k$ is any positive integer, $\mathcal{F}$ is the Fourier transformation in $\mathbb{R}^{n+1},$ $I$ is the Kelvin inversion. We show that on the monomials the action of the mapping $τ$ defined through the Kelvin inversion coincides with that of the Fueter mapping defined through the Fourier transform (the Monomial Theorem). In the mentioned 1997 paper this result is proved for the case $n$ being odd integers. The Monomial Theorem further implies that the extended mapping $τ$ on Laurent series of real coefficients is identical with the Fueter mapping defined through pointwise differentiation or the Fourier multiplier.