Invariants of the Action of a Semisimple Finite-Dimensional Hopf Algebra on Special Algebras

摘要

In this paper we extend classical results of the invariant theory of finite groups to the action of a finite-dimensional semisimple Hopf algebra H on a special algebra A, which is homomorphically mapped onto a commutative integral domain, and the kernel of this map contains no nonzero H-stable ideals. We prove that the algebra A is finitely generated as a module over a subalgebra of invariants, and the latter is finitely generated as a k-algebra.We give a counterexample to the finite generation of a non-semisimple Hopf algebra.