Galois orders

非交换D型Kleinian奇点的Galois序实现

Galois order realization of noncommutative type $D$ Kleinian singularities

本文证明D型非交换Kleinian奇点可实现为主Galois序，并计算了相应旗序的显式生成元及局部分布Harish-Chandra模的结构常数。

(ϕ,Γ)-modules over noncommutative overconvergent and Robba rings

We construct noncommutative multidimensional versions of overconvergent power series rings and Robba rings. We show that the category of étale $(φ,Γ)$-modules over certain completions of these rings are equivalent to the category of étale $(φ,Γ)$-modules over the corresponding classical overconvergent, resp. Robba rings (hence also to the category of $p$-adic Galois representations of $\mathbb{Q}_p$). Moreover, in the case of Robba rings, the assumption of étaleness is not necessary, so there exists a notion of trianguline objects in this sense.

Fibers of characters in Harish-Chandra categories

We solve the problem of extension of characters of commutative subalgebras in associative (noncommutative) algebras for a class of subrings (Galois orders) in skew group rings. These results can be viewed as a noncommutative analogue of liftings of prime ideals in the case of integral extensions of commutative rings. The proposed approach can be applied to the representation theory of many infinite dimensional algebras including universal enveloping algebras of reductive Lie algebras, Yangians and finite $W$-algebras. In particular, we develop a theory of Gelfand-Tsetlin modules for $\gl_n$. B…

Harish-Chandra modules over Hopf Galois orders

The theory of Galois orders was introduced by Futorny and Ovsienko. We introduce the notion of $\mathcal{H}$-Galois $Λ$-orders. These are certain noncommutative orders $F$ in a smash product of the fraction field of a noetherian integral domain $Λ$ by a Hopf algebra $\mathcal{H}$ (or, more generally, by a coideal subalgebra of a Hopf algebra). They are generalizations of Webster's principal flag orders. Examples include Cherednik algebras, as well as examples from Hopf Galois theory. We also define spherical Galois orders, which are the corresponding generalizations of principal Galois orders …

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

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 $n=3$ provid…

Principal Galois orders and Gelfand-Zeitlin modules

We show that the ring of invariants in a skew monoid ring contains a so called standard Galois order. Any Galois ring contained in the standard Galois order is automatically itself a Galois order and we call such rings principal Galois orders. We give two applications. First, we obtain a simple sufficient criterion for a Galois ring to be a Galois order and hence for its Gelfand-Zeitlin subalgebra to be maximal commutative. Second, generalizing a recent result by Early-Mazorchuk-Vishnyakova, we construct canonical simple Gelfand-Zeitlin modules over any principal Galois order. As an example, w…