The theory of Kaluza-Klein-Jordan-Thiry revisited
We prove that if the sectional curvature, , of a compact 6-manifold without boundary satisfies then its third (real) Betti number is zero.
We prove the Paley-Wiener theorem for the Helgason Fourier transform of smooth compactly supported 𝔳-radial functions on a Damek-Ricci space S = NA.