Eisenstein series
In mathematics, the Maass–Selberg relations are some relations describing the inner products of truncated real analytic Eisenstein series, that in some sense say that distinct Eisenstein series are orthogonal. Hans Maass introduced the Maass–Selberg relations for the case of real analytic Eisenstein series on the upper half plane. Atle Selberg extended the relations to symmetric spaces of rank 1. Harish-Chandra generalized the Maass–Selberg relations to Eisenstein series of higher rank semisimple group (and named the relations after Maass and Selberg) and found some analogous relations between Eisenstein integrals, that he also called Maass–Selberg relations.