Free Lie Algebra Of Rank Research Articles

Presentations for Subrings and Subalgebras of Finite CO-Rank

Abstract Let $K$ be a commutative Noetherian ring with identity, let $A$ be a $K$-algebra and let $B$ be a subalgebra of $A$ such that $A/B$ is finitely generated as a $K$-module. The main result of the paper is that $A$ is finitely presented (resp. finitely generated) if and only if $B$ is finitely presented (resp. finitely generated). As corollaries, we obtain: a subring of finite index in a finitely presented ring is finitely presented; a subalgebra of finite co-dimension in a finitely presented algebra over a field is finitely presented (already shown by Voden in 2009). We also discuss the role of the Noetherian assumption on $K$ and show that for finite generation it can be replaced by a weaker condition that the module $A/B$ be finitely presented. Finally, we demonstrate that the results do not readily extend to non-associative algebras, by exhibiting an ideal of co-dimension $1$ of the free Lie algebra of rank 2 which is not finitely generated as a Lie algebra.

On the dimension of the product $[L_2,L_2,L_1]$ in free Lie algebras

Let $L$ be a free Lie algebra of rank $rgeq2$ over a field $F$ and let $L_n$ denote the degree $n$ homogeneous component of $L$‎. ‎By using the dimensions of the corresponding homogeneous and fine homogeneous components of the second derived ideal of free centre-by-metabelian Lie algebra over a field $F$‎, ‎we determine the dimension of $[L_2,L_2,L_1]$‎. ‎Moreover‎, ‎by this method‎, ‎we show that the dimension of $[L_2,L_2,L_1]$ over a field of characteristic $2$ is different from the dimension over a field of characteristic other than $2$.

Free Malcev algebra of rank three

We find a basis for the free Malcev algebra on three free generators over a field of characteristic zero. The semiprimity and speciality of this algebra are proved. Also, we prove the decomposability of this algebra into a subdirect sum of the free Lie algebra of rank three and the free algebra of rank three of the variety generated by a simple seven-dimensional Malcev algebra. These results were announced in [1].

TEST RANK OF THE LIE ALGEBRA F/[R′, F

Let F be a free Lie algebra of rank n ≥ 2 and R be a fully invariant ideal of F. We show that the test rank of the Lie algebra F/[R′, F] is equal to 1 when n is even and less than or equal to 2 when n is odd.

Nonabelian 1-cohomologies and conjugacy of finite subgroups in some extensions

We describe the conjugacy classes of finite subgroups in some split extensions using the notion of 1-cocycle and 1-coboundary with values in a noncommutative group. We prove that each finite subgroup in the automorphism group of a free Lie algebra of rank 3 is conjugated with a subgroup of the linear automorphism group provided that the group order does not divide the characteristic of the ground field.

Test rank of an abelian product of a free Lie algebra and a free abelian Lie algebra

Let F be a free Lie algebra of rank n ≥ 2 and A be a free abelian Lie algebra of rank m ≥ 2. We prove that the test rank of the abelian product F ×A is m. Morever we compute the test rank of the algebra \(F/\gamma _{k}\left( F\right) ^{^{\prime }}\).

Periodic automorphisms of the free Lie algebra of rank 3

We prove that each automorphism of finite order of the free Lie algebra of rank 3 over an algebraically closed field is conjugate to a linear automorphism if the field characteristic fails to divide the automorphism order.

Some subalgebras of indefinite type Kac–Moody Lie algebras

We show that every Kac–Moody Lie algebra of indefinite type contains a subalgebra with a Dynkin diagram having two adjacent vertices whose edge labels multiply to a number greater than or equal to five. Consequently, every Kac–Moody algebra of indefinite type contains a subalgebra of strictly hyperbolic type, and a free Lie algebra of rank two.

ON THE FIXED POINTS OF A FINITE GROUP ACTING ON A RELATIVELY FREE LIE ALGEBRA

We show that if F is a free Lie algebra of rank at least 2 and if G is a non-trivial finite group of automorphisms of F then the fixed point subalgebra F^G is not finitely generated. Some similar results are proved for relatively free Lie algebras.

Free Lie algebras as modules for symmetric groups

AbstractLet r be a positive integer, F a field of odd prime characteristic p, and L the free Lie algebra of rank r over F. Consider L a module for the symmetric group , of all permutations of a free generating set of L. The homogeneous components Ln of L are finite dimensional submodules, and L is their direct sum. For p ≤ r ≤ 2p, the main results of this paper identify the non-porojective indecomposable direct summands of the Ln as Specht modules or dual Specht modules corresponding to certain partitions. For the case r = p, the multiplicities of these indecomposables in the direct decompositions of the Ln are also determined, as are the multiplicities of the projective indecomposables. (Corresponding results for p = 2 have been obtained elsewhere.)

Fixed Algebras of Residually Nilpotent Lie Algebras

Let ${L_m}$ be the free Lie algebra of rank $m > 1$ over a field $K$, and let $J$ be an ideal of ${L_m}$ such that $J \subset L_m^{''}$ and the algebra ${L_m}/J$ is residually nilpotent. Let $G \ne \langle 1\rangle$ be a finite group of automorphisms of ${L_m}/J$ and the order of $G$ be invertible in $K$. We establish that the algebra of fixed points ${({L_m}/J)^G}$ is not finitely generated. The class of algebras under consideration contains the free Lie algebra over an arbitrary field and the relatively free algebras in nonnilpotent varieties of Lie algebras over infinite fields of characteristic different from $2$ and $3$.

Dense Subgroups of the Automorphism Groups of Free Algebras

AbstractLet F be the free metabelian Lie algebra of finite rank m over a field K of characteristic 0. The automorphism group Aut F is considered with respect to a topology called the formal power series topology and it is shown that the group of tame automorphisms (automorphisms induced from the free Lie algebra of rank m) is dense in Aut F for m ≥ 4 but not dense for m = 2 and m = 3. At a more general level, we study the formal power series topology on the semigroup of all endomorphisms of an arbitrary (associative or non-associative) relatively free algebra of finite rank m and investigate certain associated modules of the general linear group GLm(AT).

On the respective terms of the derived and the polycentral series of a free lie algabra and an ideal

Let F be a free Lie algebra of rank> 1 and S be an ideal of F. Denote by Fm and Fn l,…,nk the terms of the lower central and the polycentral series of F. The aim of this paper is to provide a sufficient condition for the quotient algebra Fn l,…,nk/Sn l,…,nk to be infinitely generated. The case Fm/Sm was studied in [6] for free groups and in [ 2 ] for free Lie algebras. In this paper the following main theorem is proved : If F = F2 = S, k > 1 and ni > 1 for i=l,…, k, then Fn l…,nk/Sn l is infinitely generated.

Automorphisms of Free Nilpotent Lie Algebras

Let Fm be the free Lie algebra of rank m over a field K of characteristic 0 freely generated by the set ﹛x1,… ,xm﹜, m ≧ 2. Cohn [7] proved that the automorphism group Aut Fm of the K-algebra Fm is generated by the following automorphisms: (i) automorphisms which are induced by the action of the general linear group GLm (= GLm(K)) on the subspace of Fm spanned by ﹛x1, … ,xm﹜; (ii) automorphisms of the form x1 → x1 +f(x2,… ,xm),Xk → xk, k ≠ 1, where the polynomial f(x2,…,xm) does not depend on x1.