Actions of Hopf algebras on fully bounded Noetherian rings.
Actions of Hopf algebras on pro-semisimple noetherian algebras and their invariants
Let H be a Hopf algebra over a field k such that every finite-dimensional (left) H-module is semisimple. We give a counterpart of the first fundamental theorem of the classical invariant theory for locally finite, finitely generated (commutative) H-module algebras, and for local, complete H-module algebras. Also, we prove that if H acts on the k-algebra A = k[[X₁,...,Xₙ]] in such a way that the unique maximal ideal in A is invariant, then the algebra of invariants is a noetherian Cohen-Macaulay...
Addendum to “Hochschild cohomology of skew group rings and invariants”