Jiri Hrivnak (Czech Technical University in Prague, Czech Republic)

Twisted Cocycles of Lie Algebras and Corresponding Invariant Functions

We consider finite-dimensional complex Lie algebras. Using certain complex parameters we generalize the concept of cohomology cocycles of Lie algebras. A special case is generalization of 1-cocycles with respect to the adjoint representation - derivations. In this case we obtain various Lie and Jordan operator algebras and two one-parametric sets of linear operators. These and similar parametric sets for higher-dimensional cocycles allow us to define complex functions which are invariant under Lie isomorphisms. Such complex functions thus represent useful invariants - we show how they classify three and four-dimensional Lie algebras as well as how they apply to some eight-dimensional one-parametric nilpotent continua of Lie algebras. These functions also provide necessary criteria for existence of 1-parametric continuous contraction.