1 research outputs found
On Lie Algebras Generated by Few Extremal Elements
We give an overview of some properties of Lie algebras generated by at most 5
extremal elements. In particular, for any finite graph {\Gamma} and any field K
of characteristic not 2, we consider an algebraic variety X over K whose
K-points parametrize Lie algebras generated by extremal elements. Here the
generators correspond to the vertices of the graph, and we prescribe
commutation relations corresponding to the nonedges of {\Gamma}. We show that,
for all connected undirected finite graphs on at most 5 vertices, X is a
finite-dimensional affine space. Furthermore, we show that for
maximal-dimensional Lie algebras generated by 5 extremal elements, X is a
point. The latter result implies that the bilinear map describing extremality
must be identically zero, so that all extremal elements are sandwich elements
and the only Lie algebra of this dimension that occurs is nilpotent. These
results were obtained by extensive computations with the Magma computational
algebra system. The algorithms developed can be applied to arbitrary {\Gamma}
(i.e., without restriction on the number of vertices), and may be of
independent interest.Comment: 19 page