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In this paper, we study nullity-2 toroidal extended affine Lie algebras in the context of vertex algebras and their $\phi$-coordinated modules. Among the main results, we introduce a variant of toroidal extended affine Lie algebras,…

Quantum Algebra · Mathematics 2021-02-23 Fulin Chen , Haisheng Li , Shaobin Tan

We introduce a class of Lie algebras called admissible Lie algebras. We show that a locally finite admissible simple Lie algebra contains a nonzero maximal toral subalgebra and the corresponding root system is an irreducible locally finite…

Quantum Algebra · Mathematics 2010-06-08 Malihe Yousofzadeh

Invariant affine reflection algebras are the last and the most general known extension of affine Kac-Moody Lie algebras, introduced in recent years. We develop a method known as "affinization" to the class of invariant affine reflection…

Quantum Algebra · Mathematics 2011-09-01 Saeid Azam , S. Reza Hosseini , Malihe Yousofzadeh

In this paper, for every $\epsilon\in \mathbb{Z}$, we introduce an extension of the 2-toroidal Lie algebra by certain derivations. Based on the $\phi_\epsilon$-coordinated modules theory for vertex algebras, we give an explicit realization…

Quantum Algebra · Mathematics 2022-03-23 Fulin Chen , Huansheng Li , Nina Yu

We introduce an algebra $\mathcal H$ consisting of difference-reflection operators and multiplication operators that can be considered as a $q=1$ analogue of Sahi's double affine Hecke algebra related to the affine root system of type…

Representation Theory · Mathematics 2007-06-13 Wolter Groenevelt

This is a survey paper about affine Hecke algebras. We start from scratch and discuss some algebraic aspects of their representation theory, referring to the literature for proofs. We aim in particular at the classification of irreducible…

Representation Theory · Mathematics 2023-09-12 Maarten Solleveld

This is an expository article on representation theory of toroidal Lie algebras. We summerize all the results on representation theory of toroidal Lie algebras obtained in the last fifteen years. Apart from that a natural genaralization of…

Representation Theory · Mathematics 2007-05-23 S. Eswara Rao

We investigate the reflection theory of Nichols algebras over arbitrary coquasi-Hopf algebras with bijective antipode, generalizing previous results restricted to the pointed cosemisimple setting [47]. By establishing a braided monoidal…

Quantum Algebra · Mathematics 2026-03-06 Bowen Li , Gongxiang Liu

We completely classify and give explicit descriptions of the maximal closed subroot systems of real affine root systems. As an application we describe a procedure to get the classification of all regular subalgebras of affine Kac Moody…

Rings and Algebras · Mathematics 2018-12-10 Krishanu Roy , R. Venkatesh

In this paper, we classify irreducible representations of affine group superschemes over fields $F$ of characteristic not two in terms of those over a separable closure $F^{\mathrm{sep}}$ and their Galois twists. We also compute the…

Representation Theory · Mathematics 2024-12-30 Takuma Hayashi

Maximal parabolic subalgebras of untwisted affine Kac-Moody algebras were studied in the context of Borel-de Siebenthal theory in [13], where they were realized as certain equivariant map algebras with a non-free abelian group action. In…

Quantum Algebra · Mathematics 2025-05-21 Kudret Bostanci , Deniz Kus

The most prominent class of integrable quantum field theories in 1+1 dimensions is affine Toda theory. Distinguished by a rich underlying Lie algebraic structure these models have in recent years attracted much attention not only as test…

High Energy Physics - Theory · Physics 2007-05-23 Christian Korff

For certain Lie algebras g, we can use a Z/5Z-grading and define a quartic form and a skew-symmetric bilinear form on the degree 1 component, g_1, thereby constructing a Freudenthal triple system. The structure of the Freudenthal triple…

Representation Theory · Mathematics 2010-05-10 Fred W. Helenius

Quantum toroidal algebras (or double affine quantum algebras) are defined from quantum affine Kac-Moody algebras by using the Drinfeld quantum affinization process. They are quantum groups analogs of elliptic Cherednik algebras (elliptic…

Quantum Algebra · Mathematics 2010-04-07 David Hernandez

We introduce a new class of possibly infinite dimensional Lie algebras and study their structural properties. Examples of this new class of Lie algebras are finite dimensional simple Lie algebras containing a nonzero split torus, affine and…

Quantum Algebra · Mathematics 2007-05-23 Malihe Yousofzadeh

We construct irreducible modules for twisted toroidal Lie algebras and extended affine Lie algebras. This is done by combining the representation theory of untwisted toroidal algebras with the technique of thin coverings of modules. We…

Representation Theory · Mathematics 2010-02-12 Yuly Billig , Michael Lau

We classify irreducible finite-dimensional modules of a collection of real Lie superalgebras that includes the simple ones, their classical variants, complex Lie superalgebras after restriction of scalars, and all real Lie algebras. Our…

Representation Theory · Mathematics 2026-04-13 Siddhartha Sahi , Hadi Salmasian , Vera Serganova

We study certain types of ideals in the standard Borel subalgebra of an untwisted affine Lie algebra. We classify these ideals in terms of the root combinatorics and give an explicit formula for the number of such ideals in type $A$. The…

Rings and Algebras · Mathematics 2013-03-12 Karin Baur , Volodymyr Mazorchuk

In this paper explicit decompositions are provided of the Weyl reflections in affine Lie algebras, in terms of fundamental Weyl reflections.

q-alg · Mathematics 2009-10-30 J. Rasmussen

Highest weight categories arising in Lie theory are known to be associated with finite dimensional quasi-hereditary algebras such as Schur algebras or blocks of category $\mathcal O$. An analogue of the PBW theorem will be shown to hold for…

Representation Theory · Mathematics 2014-05-01 Steffen Koenig , Julian Külshammer , Sergiy Ovsienko