Extensions of Lie algebras
arXiv:math/0005042
Abstract
We review (non-abelian) extensions of a given Lie algebra, identify a 3-dimensional cohomological obstruction to the existence of extensions. A striking analogy to the setting of covariant exterior derivatives, curvature, and the Bianchi identity in differential geometry is spelled out. In the new version references added: Most of the results are known. So this paper will not be submitted to a journal, it can be regarded as a review paper.
AmSTeX + diag.tex, 9 pages In the new version references added: Most of the results are known. The last (wrong) statement omitted. So this paper will not be submitted to a journal, it can be regarded as a review paper