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

## TL;DR

This paper introduces a new algebra related to the universal enveloping algebra of rak{gl}_n, constructed via invariants under alternating groups, and explores its structure, representations, and connections to classical conjectures.

## Contribution

It defines the algebra alA(rak{gl}_n) as an invariant ring under alternating groups, shows it is a Galois ring, and analyzes its structure and modules, extending previous work on symmetric groups.

## Key findings

- alA(rak{gl}_n) is a Galois ring.
- For n=2, alA(rak{gl}_n) is a generalized Weyl algebra.
- Connections to Gelfand-Kirillov Conjecture and Noether's problem.

## 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 $\mathscr{A}(\mathfrak{gl}_n)$, 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 $\mathscr{A}(\mathfrak{gl}_n)$. Finally, we discuss connections between the Gelfand-Kirillov Conjecture, $\mathscr{A}(\mathfrak{gl}_n)$, and the positive solution to Noether's problem for the alternating group.