Multiple Dirichlet series over rational function fields by Gautam Chinta (New York)1. Introduction. The purpose of this paper is to explicitly compute some examples of Weyl group multiple Dirichlet series over the rational function field F q (t). As described in [2], these are Dirichlet series in r complex variables s 1 , . . . , s r whose coefficients can be expressed in terms of nth order Gauss sums. The general theory implies that over a function field, these multiple Dirichlet series will be rational functions of q −s 1 , . . . , q −sr . Except when n = 2, no examples of these rational functions have been written down.Using explicit knowledge of the functional equations, we will express the A 2 series as a rational function of q −s 1 and q −s 2 . This is the main result of this paper and is given in Theorem 4.2. The functional equations of multiple Dirichlet series arise from the functional equations of single variable Gauss sum Dirichlet series of the type initially studied by Kubota [17] using the theory of metaplectic Eisenstein series on the n-fold cover of GL 2 . This theory was further developed by Kazhdan and Patterson [16] who studied Eisenstein series on the n-fold cover of GL r . It is conjectured that the Weyl group multiple Dirichlet series are related to Whittaker coefficients of these metaplectic Eisenstein series. This conjecture and much supporting evidence for it is given in [2,4] In [2] is described a heuristic method to associate to a positive integer n, and a root system Φ of rank r, a multiple Dirichlet series Z in r complex variables with coefficients given by nth order Gauss sums. Moreover, Z is expected to have an analytic continuation to C r and to satisfy a group of functional equations isomorphic to W , the Weyl group of the root system. Brubaker, Bump, and Friedberg [3] have given a precise definition of Z in the stable case; by definition, this means n is sufficiently large for a fixed Φ. In [3] the authors show that for such n, the Weyl group multiple Dirichlet