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We study the almost Kaehler geometry of adjoint orbits of non-compact real semisimple Lie groups endowed with the Kirillov-Kostant-Souriau symplectic form and a canonically defined almost complex structure. We give explicit formulas for the…

Differential Geometry · Mathematics 2018-11-27 Alberto Della Vedova , Alice Gatti

In this paper we present a lower bound for the minimal dimension $\mu(\mathfrak{n})$ of a faithful representation of a finite dimensional $p$-step nilpotent Lie algebra $\mathfrak{n}$ over a field of characteristic zero. Our bound is given…

Representation Theory · Mathematics 2014-07-02 Leandro Cagliero , Nadina Rojas

This paper studies nilpotent orbits in complex simple Lie algebras from the viewpoint of strongly visible actions in the sense of T. Kobayashi. We prove that the action of a maximal compact group consisting of inner automorphisms on a…

Representation Theory · Mathematics 2017-12-20 Atsumu Sasaki

This is a sequel to \cite{osy} and \cite{sxy}. Associated with $G:=\GL_n$ and its rational representation $(\rho, M)$ over an algebraically closed filed $\bk$, we define an enhanced algebraic group $\uG:=G\ltimes_\rho M$ which is a product…

Representation Theory · Mathematics 2026-05-01 Bin Shu , Yunpeng Xue , Yufeng Yao

We introduce minimal Richardson orbits and pseudo-polarizations for nilpotent orbits in classical Lie algebras of types B, C, and D. For any nilpotent orbit, we classify all minimal Richardson orbits containing it and thereby determine the…

Algebraic Geometry · Mathematics 2026-02-10 Xueqing Wen , Yaoxiong Wen

In this paper we describe a multiparameter deformation of the function algebra of a semisimple coadjoint orbit. In the first section we use the representation of the Lie algebra on a generalized Verma module to quantize the Kirillov bracket…

q-alg · Mathematics 2008-02-03 Joseph Donin , Dmitry Gurevich , Steven Shnider

We establish combinatorial formulas for the index of a class of matrix Lie algebras whose matrix forms are encoded by strict partial orderings.

Rings and Algebras · Mathematics 2020-04-21 Vincent Coll , Nicholas Mayers , Nicholas Russoniello

We prove that generic higher Deligne-Lusztig representations over truncated formal power series are non-nilpotent, when the parameters are non-trivial on the biggest reduction kernel of the centre; we also establish a relation between the…

Representation Theory · Mathematics 2019-04-24 Zhe Chen

In the case of complex symplectic and orthogonal groups, we find $(\mathfrak{g}, K)-$modules with the property that their $K-$structure matches the structure of regular functions on the closures of nilpotent orbits. This establishes a…

Representation Theory · Mathematics 2022-05-17 Dan Barbasch , Kayue Daniel Wong

In this paper, we establish a general criterion for good pairs, namely pairs consisting of a nilpotent orbit and an even good grading in a simple Lie algebra, which guarantees the existence of a quantum Hamiltonian reduction between…

Representation Theory · Mathematics 2026-01-06 Justine Fasquel , Shigenori Nakatsuka

We look at the odd nilpotent orbits of osp(2n+1,2n), giving a combinatorial interpretation which enables us, via the square map, to explain the link with even nilpotent orbits. We then study the closure ordering of the odd nilpotent orbits.…

Rings and Algebras · Mathematics 2010-12-01 Caroline Gruson , Séverine Leidwanger

We give a full classification of 6-dimensional nilpotent Lie algebras over an arbitrary field, including fields that are not algebraically closed and fields of characteristic~2. To achieve the classification we use the action of the…

Rings and Algebras · Mathematics 2020-06-26 Serena Cicalo , Willem A de Graaf , Csaba Schneider

In the classification of stationary solutions in extended supergravities with symmetric scalar manifolds, the nilpotent orbits of a real symmetric pair play an important role. In this paper we discuss two approaches to determining the…

Representation Theory · Mathematics 2017-04-26 Heiko Dietrich , Willem A. de Graaf , Daniele Ruggeri , Mario Trigiante

In this paper, we shall prove that any two (projective) symplectic resolutions of a nilpotent orbit closure in a classical simple Lie algebra are connected by a finite sequence of diagrams which are locally trivial families of Mukai flops…

Algebraic Geometry · Mathematics 2007-05-23 Yoshinori Namikawa

We give an example of a compact connected Lie group of the lowest rank such that the mod 2 cohomology ring of its classifying space has a nonzero nilpotent element.

Algebraic Topology · Mathematics 2026-01-13 Masaki Kameko

We consider the conjugation-action of the Borel subgroup of the symplectic or the orthogonal group on the variety of nilpotent complex elements of nilpotency degree $2$ in its Lie algebra. We translate the setup to a…

Representation Theory · Mathematics 2019-02-11 Magdalena Boos , Giovanni Cerulli Irelli , Francesco Esposito

The orbital varieties are the irreducible components of the intersection between a nilpotent orbit and a Borel subalgebra of the Lie algebra of a reductive group. There is a geometric correspondence between orbital varieties and irreducible…

Representation Theory · Mathematics 2018-10-31 Lucas Fresse , Anna Melnikov

We give tables of noncompact real forms of maximal reductive subalgebras of complex simple Lie algebras of rank up to 8. These were obtained by computational methods that we briefly describe. We also discuss applications in theoretical…

Rings and Algebras · Mathematics 2020-05-20 Willem A. de Graaf , Alessio Marrani

In this article, we study adjoint orbits of the Jacobi group, and in particular describe nilpotent orbits explicitely.

Algebraic Geometry · Mathematics 2017-06-14 Yong-Jae Kwon , Jae-Hyun Yang

Let g be a real form of a simple complex Lie algebra. Based on ideas of Djokovic and Vinberg, we describe an algorithm to compute representatives of the nilpotent orbits of g using the Kostant-Sekiguchi correspondence. Our algorithms are…

Rings and Algebras · Mathematics 2012-09-26 Heiko Dietrich , Willem A. de Graaf