Degenerate Eisenstein series on symplectic groups

In this paper we describe the generalization of usual notion of Siegel Eisenstein series (see for example [9]) to give a simple and natural construction of some classes of square-integrable automorphic representations for symplectic groups. The construction of automorphic representations obtained in this paper is an automorphic version of the local construction of strongly negative unramified representations [5](1) or of discrete series obtained by Tadic [11] in early 90's (see also later work [8]). This is taken from our paper [7]. As an application we show how one can obtain an automorphic realization of certain global spherical representations. This has an interesting consequence locally and globally. We adopt Arthur's point of view (see [2]).