https://doi.org/10.1007/978-3-319-90878-6In this Chapter we introduce and study the operator E(λ), which acts on the space of functions on the sphere .. It is used in all subsequent Chapters.
https://doi.org/10.1007/978-3-531-19631-2In this Chapter we consider operators of the form A = F.Ф(ξ)F., where F is the Fourier transform on ., and Ф is a positively homogeneous function of complex degree ., i.e. Ф(.) = .Ф(. for . ∈.