### Some Remarks on Harmonic Projection Operators on Spheres

#### Abstract

We give a survey of recent works concerning the mapping properties of joint harmonic projection operators, mapping the space of square integrable functions on complex and quaternionic spheres onto the eigenspaces of the Laplace-Beltrami operator and of a suitably defined subLaplacian. In particular, we discuss similarities and differences between the real, the complex and the quaternionic framework.

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DOI: 10.6092/issn.2240-2829/6685

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