Central Extensions of Steinberg Lie Superalgebras of Small Rank

It was shown by Mikhalev and Pinchuk (2000 Mikhalev , A. V. , Pinchuk , I. A. ( 2000 ). Universal central extensions of the matrix Lie superalgebras sl(m,n,A) . Int. Conf. in H.K.U., AMS , 111 – 125 . [Google Scholar]) that the second homology group H ₂(𝔰𝔱(m,n,R)) of the Steinberg Lie superalgebra 𝔰𝔱(m,n,R) is trivial for m + n ≥ 5. In this article, we will work out H ₂(𝔰𝔱(m,n,R)) explicitly for m + n = 3, 4.     

Quasi-Deformations of 𝔰𝔩2(𝔽) Using Twisted Derivations

In this article we apply a method devised in Hartwig, Larsson, and Silvestrov (2006 Hartwig , J. T. , Larsson , D. , Silvestrov , S. D. ( 2006 ). Deformations of Lie algebras using σ-derivations . J. Algebra 295 : 314 – 361 .[Crossref], [Web of Science ®] , [Google Scholar]) and Larsson and Silvestrov (2005a Larsson , D. , Silvestrov , S. D. (2005a). Quasi-hom-Lie algebras, Central extensions and 2-cocycle-like identities. J. Algebra 288:321–344.[Crossref], [Web of Science ®] , [Google Scholar]) to the simple 3-dimensional Lie algebra 𝔰𝔩₂(𝔽). One of the main points of this deformation method is that the deformed algebra comes endowed with a canonical twisted Jacobi identity. We show in the present article that when our deformation scheme is applied to 𝔰𝔩₂(𝔽) we can, by choosing parameters suitably, deform 𝔰𝔩₂(𝔽) into the Heisenberg Lie algebra and some other 3-dimensional Lie algebras in addition to more exotic types of algebras, this being in stark contrast to the classical deformation schemes where 𝔰𝔩₂(𝔽) is rigid.     

On the Cohomology of the Lie Superalgebra of Contact Vector Fields on S 1|m

The main result of this article is the explicit calculation of the first cohomology space H ¹(𝒦(3), 𝒮Ψ𝒟𝒪(S ^1|3)) of the Lie superalgebra 𝒦(3) of contact vector fields on the supercircle S ^1|3 with coefficients in the module of superpseudodifferential operators 𝒮Ψ𝒟𝒪(S ^1|3). For the supercicles of dimensional 1 | 0, 1 | 1, and 1 | 2, the first cohomology space is computed, respectively, in the following articles: [2 Agrebaoui , B. , Ben Fraj , N. ( 2004 ). On the cohomology of the Lie superalgebra of contact vector fields on S ^1|1 . Belletin de la Société Royale des Sciences de Liège 72 ( 6 ): 365 – 375 . [Google Scholar], 3 Agrebaoui , B. , Ben Fraj , N. , Omri , S. ( 2006 ). On the cohomology of the Lie superalgebra of contact vector fields on S ^1|2 . J. Nonlinear Math. Phys. 13 ( 4 ): 523 – 534 .[Taylor &; Francis Online] , [Google Scholar], 14 Ovsienko , V. , Roger , C. ( 1999 ). Deforming the Lie algebra of vector fields on S ¹ inside the Lie algebra of pseudodifferential operators on S ¹ . AMS Transl. Ser. 2, (Adv. Math. Sci.) 194 : 211 – 227 . [Google Scholar]]. The case m ≥ 4 is still out of reach, but we give a lower bound for the dimension of the cohomology space and exhibit three nontrivial, 1-cocycles.     

The infinitesimal and the little q-Schur superalgebras

In this paper, based on the results in [8 Du, J., Gu, H.-X. (2014). A realization of the quantum supergroup U(𝔤𝔩_m|n). J. Algebra 404:60–99.[Web of Science ®] , [Google Scholar]] we give a monomial basis for q-Schur superalgebra and then a presentation for it. The presentation is different from that in [12 El Turkey, H., Kujawa, J. (2012). Presenting Schur superalgebras. Pacific J. Math., 262(2):285–316.[Crossref], [Web of Science ®] , [Google Scholar]]. Imitating [3 Cox, A. G. (1997). On some applications of infinitesimal methods to quantum groups and related algebras. Ph.D. Thesis. University of London. [Google Scholar]] and [7 Du, J., Fu, Q., Wang, J.-P. (2005). Infinitesimal quantum 𝔤𝔩_n and little q-Schur algebras. J. Algebra 287:199–233.[Crossref], [Web of Science ®] , [Google Scholar]], we define the infinitesimal and the little q-Schur superalgebras. We give a “weight idempotent presentation” for infinitesimal q-Schur superalgebras. The BLM bases and monomial bases of little q-Schur superalgebras are obtained, and dimension formulas of infinitesimal and little q-Schur superalgebras are deduced.     

About the Cohomology of the Lie Superalgebra of Vector Fields on ℝ n|n

In this article, we compute the first space of cohomology of Vect (? ^n|n ), the Lie superalgebra of vector fields on the supermanifold ? ^n|n with coefficients in 𝒻 (? ^n|n ), the space of smooth functions on ? ^n|n . We give a super analog of the cohomologies of vector fields that where studied for instance by Fuchs [2 Fuchs , D. B. ( 1986 ). Cohomology of Infinite Dimensional Lie Algebras . New York : Consultants Bureau . [Google Scholar]]. This work allows us to classify the deformations of the action of Vect(? ^n|n ) on 𝒻 (? ^n|n ).     

Notes on Two-Parameter Quantum Groups, (II)

This article is the sequel to [11 Hu , N. , Pei , Y. ( 2008 ). Notes on two-parameter quantum groups, (I) . Sci. in China, Ser. A 51 ( 6 ): 1101 – 1110 . [Google Scholar]] to study the deformed structures and representations of two-parameter quantum groups U _{r, s} (𝔤) associated to the finite dimensional simple Lie algebras 𝔤. An equivalence of the braided tensor categories 𝒪 ^{r, s} and 𝒪 ^q under the assumption rs ^?1 = q ² is explicitly established.     

Direct Limits of Diagonal Chains of Type O,U, and Sp,and Their Homotopy Groups

ABSTRACT

Baranov and Zhilinskii (1999 Baranov , A. A. , Zhilinskii , A. G. ( 1999 ). Diagonal direct limits of simple Lie algebras . Comm. Algebra 27 ( 6 ): 2749 – 2766 [CSA] [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) have shown a classification theorem for diagonal direct limits of simple Lie algebras. In this work, we will transfer their results to diagonal direct limits of certain matrix groups, and show that homotopy groups are significant invariants for specific classes of direct limit groups.

Communicated by B. Allison     

Simple Nil Lie Algops

A Lie algop is a pair (A, L) where A is a commutative algebra and L is a Lie algebra operating on A by derivations. Faithful simple Lie algops (A, L) are of interest because the corresponding Lie algebras AL are simple—with some rare exceptions at characteristic 2. The simplicity and representation theory of Jordan Lie algops is reduced in Winter (2005b Winter , D. J. ( 2005b ). Lie algops and simple Lie algebras . Comm. Algebra 33 : 3157 – 3178 .[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) to the simplicity theory of nil Lie algops and the simplicity and representation theory of toral Lie algops. This paper is devoted to building the first of these two theories, the simplicity theory of nil Lie algops, as a structure theory.     

On Free Sabinin Algebras

Sabinin algebras are algebraic objects that capture the local structure of analytic loops in the same way in which Lie algebras capture the local structure of Lie groups. They were introduced by Sabinin and Mibeev [13 Sabinin , L. V. , Miheev , P. O. (1987). On the infinitesimal theory of local analytic loops. Dokl. Akad. Nauk SSSR 297:801–804 (in Russian). English trans.: Soviet Math. Dokl. (1988), 36:545–548. [Google Scholar]].

In 1962, Shirshov [20 Shtern , A. S. ( 1986 ). Free Lie superalgebras . Sibirsk. Mat. Z. 27 : 170 – 174 (in Russian) . [Google Scholar]] suggested a scheme for choosing bases of a free Lie algebra that generalizes the Hall and Lyndon–Shirshov bases. In this article, we generalize the Shirshov scheme for the case of Sabinin algebras.     

Generalizations of Groups in which Normality Is Transitive

A group G is called a Hall_𝒳-group if G possesses a nilpotent normal subgroup N such that G/N′ is an 𝒳-group. A group G is called an 𝒳_o-group if G/Φ(G) is an 𝒳-group. The aim of this article is to study finite solvable Hall_𝒳-groups and 𝒳_o-groups for the classes of groups 𝒯, 𝒫𝒯, and 𝒫𝒮𝒯. Here 𝒯, 𝒫𝒯, and 𝒫𝒮𝒯 denote, respectively, the classes of groups in which normality, permutability, and Sylow-permutability are transitive relations. Finite solvable 𝒯-groups, 𝒫𝒯-groups, and 𝒫𝒮𝒯-groups were globally characterized, respectively, in Gaschütz (1957 Gaschütz , W. ( 1957 ). Gruppen, in denen das normalteilersein transitiv ist . J. Reine Angew. Math. 198 : 87 – 92 .[Crossref] , [Google Scholar]), Zacher (1964 Zacher , G. ( 1964 ). I gruppi risolubili finiti in cui i sottogruppi di composizione coincidono con i sottogruppi quasi-normali . Atti Accad. Naz. Lincei Rend. Cl. Sci. Fis. Mat. Natur. (8) 37 : 150 – 154 . [Google Scholar]), and Agrawal (1975 Agrawal , R. K. ( 1975 ). Finite groups whose subnormal subgroups permute with all Sylow subgroups . Proc. Amer. Math. Soc. 47 : 77 – 83 .[Crossref], [Web of Science ®] , [Google Scholar]). Here we arrive at similar characterizations for finite solvable Hall_𝒳-groups and 𝒳_o-groups where 𝒳 ∈ {𝒯, 𝒫𝒯, 𝒫𝒮𝒯}. A key result aiding in the characterization of these groups is their possession of a nilpotent residual which is a nilpotent Hall subgroup of odd order. The main result arrived at is Hall_𝒫𝒮𝒯 = 𝒯_o for finite solvable groups.     

On the Classification of Orbits of Symmetric Subgroups Acting on Flag Varieties of SL(2, k)

Symmetric k-varieties are a generalization of symmetric spaces to general fields. Orbits of a minimal parabolic k-subgroup acting on a symmetric k-variety are essential in the study of symmetric k-varieties and their representations. In this article, we present the classification of these orbits for the group SL(2,k) for a number of base fields k, including finite fields and the 𝔭-adic numbers. We use the characterization in Helminck and Wang (1993 Helminck , A. G. , Wang , S. P. ( 1993 ). On rationality properties of involutions of reductive groups . Adv. Math. 99 ( 1 ): 26 – 96 .[Crossref], [Web of Science ®] , [Google Scholar]), which requires one to first classify the orbits of the θ-stable maximal k-split tori under the action of the k-points of the fixed point group.     

Nil Lie p-algebras of slow growth

The Grigorchuk and Gupta-Sidki groups play fundamental role in modern group theory. They are natural examples of self-similar finitely generated periodic groups. The author constructed their analogue in case of restricted Lie algebras of characteristic 2 [27 Petrogradsky, V. M. (2006). Examples of self-iterating Lie algebras. J. Algebra 302(2):881–886.[Crossref], [Web of Science ®] , [Google Scholar]], Shestakov and Zelmanov extended this construction to an arbitrary positive characteristic [39 Shestakov, I. P., Zelmanov, E. (2008). Some examples of nil Lie algebras. J. Eur. Math. Soc. (JEMS) 10(2):391–398.[Crossref], [Web of Science ®] , [Google Scholar]]. There are a few more examples of self-similar finitely generated restricted Lie algebras with a nil p-mapping, but, as a rule, that algebras have no clear basis and require technical computations. Now we construct a family L(Ξ) of 2-generated restricted Lie algebras of slow polynomial growth with a nil p-mapping, where a field of positive characteristic is arbitrary and Ξ an infinite tuple of positive integers. Namely, GKdimL(Ξ)≤2 for all such algebras. The algebras are constructed in terms of derivations of infinite divided power algebra Ω. We also study their associative hulls A?End(Ω). Algebras L and A are ?²-graded by a multidegree in the generators. If Ξ is periodic then L(Ξ) is self-similar. As a particular case, we construct a continuum subfamily of non-isomorphic nil restricted Lie algebras L(Ξ_α), α∈?⁺, with extremely slow growth. Namely, they have Gelfand-Kirillov dimension one but the growth is not linear. For this subfamily, the associative hulls A have Gelfand-Kirillov dimension two but the growth is not quadratic. The virtue of the present examples is that they have clear monomial bases.