Weil Representation of a Generalized Linear Group over a Ring of Truncated Polynomials over a Finite Field Endowed with a Second Class Involution

Abstract

We construct a complex linear Weil representation ρ of the generalized special linear group G=SL¹∗(2,An) (An=K[x]/⟨xⁿ⟩, K the quadratic extension of the finite field k of q elements, q odd), where An is endowed with a second class involution. After the construction of a specific data, the representation is defined on the generators of a Bruhat presentation of G, via linear operators satisfying the relations of the presentation. The structure of a unitary group U associated to G is described. Using this group we obtain a first decomposition of ρ.