In ref. [1],Fisher studied the Hopf-Jacobson radical for Hopf module algebras, in which,when k is a field, it is required that the Hopf algebra H is irreducible as a coalgebra;that is, H contains a unique simple subco...
R. J. Blattner and S. Montgomery have proved the duality theorem of Hopf module algebras in Ref. [1]. This theorem contains duality for crossed product of von Neumann algebras. In 1977, R. K. Molnar introduced the con...
Let G be an arbitrary group with identity e. Let A be a G-graded ring with identity 1, i. e. A= Ag (direct sums of additive groups), with property AgAh Agh. The smash prod-