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Algebraically generated groups and their Lie algebras
Journal of the London Mathematical Society ( IF 1.2 ) Pub Date : 2024-02-07 , DOI: 10.1112/jlms.12866 Hanspeter Kraft 1 , Mikhail Zaidenberg 2
Journal of the London Mathematical Society ( IF 1.2 ) Pub Date : 2024-02-07 , DOI: 10.1112/jlms.12866 Hanspeter Kraft 1 , Mikhail Zaidenberg 2
Affiliation
The automorphism group of an affine variety is an ind-group. Its Lie algebra is canonically embedded into the Lie algebra of vector fields on . We study the relations between subgroups of and Lie subalgebras of . We show that a subgroup generated by a family of connected algebraic subgroups of is algebraic if and only if the Lie algebras generate a finite-dimensional Lie subalgebra of . Extending a result by Cohen–Draisma (Transform. Groups 8 (2003), no. 1, 51–68), we prove that a locally finite Lie algebra generated by locally nilpotent vector fields is algebraic, that is, for an algebraic subgroup . Along the same lines, we prove that if a subgroup generated by finitely many connected algebraic groups is solvable, then it is an algebraic group. We also show that a unipotent algebraic subgroup has derived length . This result is based on the following triangulation theorem: Every unipotent algebraic subgroup of with a dense orbit in is conjugate to a subgroup of the de Jonquières subgroup. Furthermore, we give an example of a free subgroup generated by two algebraic elements such that the Zariski closure is a free product of two nested commutative closed unipotent ind-subgroups. To any affine ind-group , one can associate a canonical ideal . It is linearly generated by the tangent spaces for all algebraic subsets that are smooth in . It has the important property that for a surjective homomorphism , the induced homomorphism is surjective as well. Moreover, if is a subnormal closed ind-subgroup of finite codimension, then has finite codimension in .
中文翻译:
代数生成群及其李代数
自同构群 仿射簇的 是一个 ind 基团。它的李代数规范地嵌入到李代数中 的向量场 。我们研究子群之间的关系 和李子代数 。我们证明一个子群 由一系列相连的代数子群生成 的 是代数当且仅当李代数 生成有限维李子代数 。扩展Cohen-Draisma的结果(Transform. Groups 8 (2003), no. 1, 51–68),我们证明局部有限李代数 由局部幂零向量场生成是代数的,即 对于代数子群 。同样,我们证明如果一个子群 由有限多个连通代数群生成的方程可解,则它是代数群。我们还证明了单能代数子群 已导出长度 。该结果基于以下三角剖分定理: 具有密集轨道 与 de Jonquières 子群 的一个子群共轭。此外,我们还给出了一个自由子群的例子 由两个代数元素生成,使得 Zariski 闭包 是两个嵌套交换闭合单能 ind 子群的自由积。对于任意仿射 ind 群 ,人们可以联想到一个规范理想 。它是由切空间线性生成的 对于所有代数子集 是光滑的 。它具有一个重要的性质:对于满射同态 ,诱导同态 也是满射的。此外,如果 是有限余维次正规闭 ind 子群,则 具有有限余维数 。
更新日期:2024-02-07
中文翻译:
代数生成群及其李代数
自同构群