Extended distributive law: Cowreath over corings

Abstract

We introduce and study comodules over cowreath defined over a given coring. If our coring arises from an entwining structure, we then give a procedure to construct a cowreath from a given cowreath over the factor coalgebra. We also include the dual notions, that is, wreaths over ring extension and their modules. In particular, we show that the study of twisted algebras and twisted bimodules already introduced in [A. ap, H. Schichl and J. Vanura, On twisted tensor products of algebras, Commun. Algebra 23 (1995) 47014735] has its origin in the study of wreath and their bimodules. © 2010 World Scientific Publishing Company.