Primitive Ideals in Hopf Algebra Extensions

Let H be a finite-dimensional Hopf algebra. We study the behaviour of primitive and maximal ideals in certain types of ring extensions determined by H . The main focus is on the class of faithfully flat Galois extensions, which includes includes smash and crossed products. It is shown how analogous results can be obtained for the larger class of extensions possessing a total integral, which includes extensions A ⊆ A when H is semisimple. We use Passman’s “primitivity machine” to reduce the whole theory of Krull relations for prime ideals to the case of primitive ideals. The concept of strongly semiprimitive Hopf algebra is introduced and investigated. Several examples and open problems are discussed.