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We study simple $\mathfrak{sl}(2)$-modules over $\mathbb C$ that are free of finite rank as $U(\mathfrak h)$-modules, where $\mathfrak h$ is a Cartan subalgebra of $\mathfrak{sl}(2)$. Our main result is an explicit classification of the…

Representation Theory · Mathematics 2026-01-30 Dimitar Grantcharov , Khoa Nguyen , Kaiming Zhao

Let $\g$ be an arbitrary Kac-Moody algebra with a Cartan sualgebra $\h$. In this paper, we determine the category of $\g$-modules that are free $U(\h)$-modules of rank 1.

Representation Theory · Mathematics 2016-07-06 Yan-an Cai , Haijun Tan , Kaiming Zhao

We study two categories of ${U}(\mathfrak h)$-free $\mathfrak{sl}(m|n)$-modules of total rank 2: $\mathcal{M}_{\mathfrak{sl}(m|n)}(2)$, whose objects are free of rank 2 over ${U}(\mathfrak h)$ which are not necessarily $\mathbb Z_2$-graded,…

Representation Theory · Mathematics 2025-10-30 Ivan Dimitrov , Khoa Nguyen

This paper builds upon J. Nilsson's classification of rank one $\mathcal{U}(\mathfrak{h})$-free modules by extending the analysis to modules without rank restrictions, focusing on the category $\mathfrak{A}$ of…

Representation Theory · Mathematics 2025-05-14 Eduardo M. Mendonça

We study the category M consisting of U(sl_{n+1})-modules whose restriction to U(h) is free of rank 1, in particular we classify isomorphism classes of objects in M and determine their submodule structure. This leads to new…

Representation Theory · Mathematics 2017-07-11 Jonathan Nilsson

In this paper, we consider some non-weight modules over the Lie algebra of Weyl type. First, we determine the modules whose restriction to $U(\frak h)$ are free of rank $1$ over the Lie algebra of differential operators on the circle. Then…

Representation Theory · Mathematics 2022-12-06 Munayim Dilxat , Shoulan Gao , Dong Liu , Limeng Xia

We study the category $\mathcal{M}_{\mathfrak{sl}(m|1)}(k|k)$ of $\mathcal U(\mathfrak h)\text{-free}$ $\mathcal U(\mathfrak{sl}(m|1))$-modules of rank $k$ in each parity (rank $(k|k)$), where $k\in\mathbb{Z}_{\geq1}$. We construct an…

Representation Theory · Mathematics 2025-10-28 Ivan Dimitrov , Khoa Nguyen , Charles Paquette , David Wehlau

In this thesis we classify modules over a Witt-type Lie algebra and superalgebra such that when considered as modules of $\mathcal{U}(\mathfrak{h})$ they are free of rank 1. We provide sufficient conditions for simplicity, and compute the…

Representation Theory · Mathematics 2020-10-20 Sarah Williamson

In this paper, we construct a family of non-weight modules over the super-Virasoro algebras. Those modules when regarded as modules of the Ramond algebra and further restricted as modules over the Cartan subalgebra $\mathfrak{h}$ are free…

Representation Theory · Mathematics 2020-07-09 Hengyun Yang , Yufeng Yao , Limeng Xia

In this paper, a family of non-weight modules over Lie superalgebras $S(q)$ of Block type are studied. Free $U(\eta)$-modules of rank $1$ over Ramond-Block algebras and free $U(\mathfrak{h})$-modules of rank $2$ over Neveu-Schwarz-Block…

Representation Theory · Mathematics 2021-01-27 Yucai Su , Xiaoqing Yue , Xiaoyu Zhu

In this paper, we study the category of modules over the Smith algebra which are free of finite rank over the unital polynomial subalgebra generated by the Cartan element $h$ and obtain families of such simple modules of arbitrary rank. In…

Representation Theory · Mathematics 2023-12-05 Vyacheslav Futorny , Samuel A. Lopes , Eduardo M. Mendonça

This paper is devoted to constructing simple modules of the planar Galilean conformal algebra. We study the tensor products of finitely many simple $\mathcal{U}(\mathcal{H})$-free modules with an arbitrary simple restricted module, where…

Representation Theory · Mathematics 2025-07-30 Dashu Xu

The classification problem for simple $\mathfrak{sl}(2)$-modules leads in a natural way to the study of the category of finite rank torsion free $\mathfrak{sl}(2)$-modules and its subcategory of rational $\mathfrak{sl}(2)$-modules. We prove…

Representation Theory · Mathematics 2021-05-17 F. J. Plaza Martín} , C. Tejero Prieto

We construct a class of non-weight modules over the twisted $N=2$ superconformal algebra $\T$. Let $\mathfrak{h}=\C L_0\oplus\C G_0$ be the Cartan subalgebra of $\T$, and let $\mathfrak{t}=\C L_0$ be the Cartan subalgebra of even part…

Representation Theory · Mathematics 2021-02-26 Haibo Chen , Xiansheng Dai , Mingqiang Liu

In this paper, we construct a new class of modules over the Block algebra $\BB(q)$, where $q$ is a nonzero complex number. We determined the irreducibilities of these modules and the isomorphisms among them.

Representation Theory · Mathematics 2018-01-11 Xuewen Liu , Xiangqian Guo

For all $k \ge 2$, we show that there exists a group $G$ and a non-free stably free $\mathbb{Z} G$-module of rank $k$. We use this to show that, for all $k \ge 2$, there exist homotopically distinct finite $2$-complexes with fundamental…

Algebraic Topology · Mathematics 2025-10-15 John Nicholson

In this note we settle some technical questions concerning finite rank quasi-free Hilbert modules and develop some useful machinery. In particular, we provide a method for determining when two such modules are unitarily equivalent. Along…

Functional Analysis · Mathematics 2007-05-23 Ronald G. Douglas , Gadadhar Misra

Let $\mathfrak{p}$ be a parabolic subalgebra of $\mathfrak{sl}(V)$ of maximal dimension and let $\mathfrak{n} \subset \mathfrak{p}$ be the corresponding nilradical. In this paper we classify the set of $\mathfrak{sl}(V)$-modules whose…

Representation Theory · Mathematics 2019-03-25 Jonathan Nilsson

In this work we study a kind of coherence condition on FI_G-modules, which generalizes the usual notion of finite generation. We prove that a module is coherent, in the appropriate sense, if and only if its generators, as well as its…

K-Theory and Homology · Mathematics 2016-06-15 Eric Ramos

For $k \ge 1$ we consider the $K$-algebra $H(k) := H(C,kD,\Omega)$ associated to a symmetrizable Cartan matrix $C$, a symmetrizer $D$, and an orientation $\Omega$ of $C$, which was defined in Part 1. We construct and analyse a reduction…

Representation Theory · Mathematics 2018-05-17 Christof Geiss , Bernard Leclerc , Jan Schröer
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