Front. Math. China All Journals

Aug 2011, Volume 6 Issue 4

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  • EDITORIAL
    Lie algebras and related topics
    Yucai Su, Shaobin Tan, Hechun Zhang
  • SURVEY ARTICLE
    Parafermion vertex operator algebras
    Chongying Dong, Qing Wang

    This paper reviews some recent results on the parafermion vertex operator algebra associated to the integrable highest weight module L(k, 0) of positive integer level k for any affine Kac-Moody Lie algebra ĝ, where g is a finite dimensional simple Lie algebra. In particular, the generators and the C 2-cofiniteness of the parafermion vertex operator algebras are discussed. A proof of the well-known fact that the parafermion vertex operator algebra can be realized as the commutant of a lattice vertex operator algebra in L(k, 0) is also given.

  • RESEARCH ARTICLE
    On classification of n-Lie algebras
    Ruipu Bai, Guojie Song, Yaozhong Zhang

    In this paper, we prove the isomorphic criterion theorem for (n+2)-dimensional n-Lie algebras, and give a complete classification of (n + 2)-dimensional n-Lie algebras over an algebraically closed field of characteristic zero.

  • RESEARCH ARTICLE
    Twisted fermionic and bosonic representations for a class of BC-graded Lie algebras
    Fulin Chen, Shaobin Tan

    In this paper, we study the fermionic and bosonic representations for a class of BC-graded Lie algebras coordinatized by skew Laurent polynomial rings. This generalizes the fermionic and bosonic constructions for the affine Kac-Moody algebras of type A N (2).

  • RESEARCH ARTICLE
    Schrödinger-Virasoro type Lie bialgebra: a twisted case
    Huanxia Fa, Yanjie Li, Junbo Li

    In this paper, we investigate Lie bialgebra structures on a twisted Schrödinger-Virasoro type algebra L. All Lie bialgebra structures on L are triangular coboundary, which is different from the relative result on the original Schrödinger-Virasoro type Lie algebra. In particular, we find for this Lie algebra that there are more hidden inner derivations from itself to LL and we develop one method to search them.

  • RESEARCH ARTICLE
    Generating index of finite-dimensional Lie algebras
    Fang Fang, Fuhai Zhu

    The notion of generating index of Lie algebras is introduced. We characterize some Lie algebras with full generating index and classify the Lie algebras with generating index 2 and 3. As a corollary, we give a characterization of 2-step nilpotent Lie algebras.

  • RESEARCH ARTICLE
    First cohomology group of rank two Witt algebra to its Larsson modules
    Jinglian Jiang, Xiaoli Kong

    Let U = ℂ2, Γ = ℤ2, and let ℂ[x 1 ±1, x 2 ±1] be the ring of Laurent polynomials. The Witt algebra L is the Lie algebra of derivations over ℂ[x 1 ±1, x 2 ±1], which is spanned by elements of the form D(u, r) = x r(u 1 d 1 + u 2 d 2), u = (u 1, u 2) ∈ U, r ∈ Γ, where d 1 and d 2 are the degree derivations of ℂ[x 1 ±1, x 2 ±1]. The image of gl 2-module V under Larsson functor F α, denoted by W = F α(V), gives a class of L-modules, often called the Larsson-modules of L. In this paper, we study the derivations from the Witt algebra L to its Larsson-modules W, and we determine the first cohomology group H 1(L,W).

  • RESEARCH ARTICLE
    Associating quantum vertex algebras to deformed Heisenberg Lie algebras
    Haisheng Li

    We associate quantum vertex algebras and their ϕ-coordinated quasi modules to certain deformed Heisenberg algebras.

  • RESEARCH ARTICLE
    Whittaker modules for a Lie algebra of Block type
    Bin Wang, Xinyun Zhu

    In this paper, we study Whittaker modules for a Lie algebra of Block type. We define Whittaker modules and under some conditions, obtain a bijective correspondence between the set of isomorphism classes of Whittaker modules over this algebra and the set of ideals of a polynomial ring, parallel to a result from the classical setting and the case of the Virasoro algebra.

  • RESEARCH ARTICLE
    Second cohomology group of extended W-algebras
    Wei Wang, Yongping Wu, Chunguang Xia

    Let F be a field of characteristic 0, and let G be an additive subgroup of F. We define a class of infinite-dimensional Lie algebras [inline-graphic not available: see fulltext] with an F-basis {L µ, V µ, W µ | µ ∈ G}, which are very closely related to W-algebras. In this paper, the second cohomology group of [inline-graphic not available: see fulltext] is determined.

  • RESEARCH ARTICLE
    Partial differential equation approach to F 4
    Xiaoping Xu

    Singular vectors of a representation of a finite-dimensional simple Lie algebra are weight vectors in the underlying module that are nullified by positive root vectors. In this article, we use partial differential equations to explicitly find all the singular vectors of the polynomial representation of the simple Lie algebra of type F 4 over its 26-dimensional basic irreducible module, which also supplements a proof of the completeness of Brion’s abstractly described generators. Moreover, we show that the number of irreducible submodules contained in the space of homogeneous harmonic polynomials with degree k ⩾ 2 is greater than or equal to 〚k/3〛 + 〚(k − 2)/3〛 + 2.

  • RESEARCH ARTICLE
    Support varieties of semisimple-character representations for Cartan type Lie algebras
    Yufeng Yao, Bin Shu

    In this paper, we study the support varieties for Lie algebras L of Cartan type. We give some description for the support varieties of any finitedimensional L-module with character χ, whenever the height of the character χ is not too large. And a more concrete computation can be made for a class of modules with semisimple characters.

  • RESEARCH ARTICLE
    Ideals and simplicity of unitary Lie algebras
    Yelong Zheng, Zhihua Chang, Yun Gao

    Double graded ideals and simplicity of elementary unitary Lie algebra eu n(R,, γ) and Steinberg unitary Lie algebra stu n(R,, γ) are characterized, where R is a unital involutory associative algebra over a field F of characteristic zero, n ⩾ 5.