# Gelfand-Kirillov dimensions of simple modules over twisted group algebras $k \ast A$

## TL;DR

This paper investigates the possible Gelfand-Kirillov dimensions of simple modules over multiparameter quantum tori, revealing a range of characteristic values under certain algebraic conditions, and extends previous results to non-simple cases.

## Contribution

It characterizes the set of Gelfand-Kirillov dimensions of simple modules over twisted group algebras under broad conditions, including non-simple cases.

## Key findings

- Identifies characteristic sets of GK dimensions for simple modules.
- Shows a dichotomy in GK dimensions even when the algebra is not simple.
- Extends previous results to more general algebraic settings.

## Abstract

For the $n$-dimensional multiparameter quantum torus algebra $\Lambda_{\mathfrak q}$ over a field $k$ defined by a multiplicatively antisymmetric matrix $\mathfrak q = (q_{ij})$ we show that in the case when the torsion-free rank of the subgroup of $k^\times$ generated by the $q_{ij}$ is large enough there is a characteristic set of values (possibly with gaps) from $0$ to $n$ that can occur as the Gelfand--Kirillov dimension of simple modules. The special case when $\mathrm{K}.\dim(\Lambda_{\mathfrak q}) = n - 1$ and $\Lambda_{\mathfrak q}$ is simple studied in A.~Gupta, {\it $\uppercase{\mbox{GK}}$-dimensions of simple modules over $K[X^{\pm 1}, \sigma]$}, Comm. Algebra, {\bf 41(7)} (2013), 2593--2597 is considered without assuming simplicity and it is shown that a dichotomy still holds for the GK dimension of simple modules.