An extension of $U({\mathfrak{gl}}_n)$ related to the alternating group and Galois orders

Abstract

In 2010, V. Futorny and S. Ovsienko gave a realization of $U({\mathfrak{gl}}_n)$ as a subalgebra of the ring of invariants of a certain noncommutative ring with respect to the action of $S_1\times S_2\times \cdots \times S_n$, where $S_j$ is the symmetric group on $j$ variables. An interesting question is what a similar algebra would be in the invariant ring with respect to a product of alternating groups. In this paper we define such an algebra, denoted $\mathcal{A}({\mathfrak{gl}}_n)$, and show that it is a Galois ring. For $n=2$, we show that it is a generalized Weyl algebra, and for $n=3$ provide generators and a list of verified relations. We also discuss some techniques to construct Galois orders from Galois rings. Additionally, we study categories of finite-dimensional modules and generic Gelfand-Tsetlin modules over $\mathcal{A}({\mathfrak{gl}}_n)$. Finally, we discuss connections between the Gelfand-Kirillov Conjecture, $\mathcal{A}({\mathfrak{gl}}_n)$, and the positive solution to Noether's problem for the alternating group.

16 pages, v4: Updated to reflect accepted manuscript to appear in Journal of Algebra