Towers of corings
arXiv:math/0201014
Abstract
The notion of a Frobenius coring is introduced, and it is shown that any such coring produces a tower of Frobenius corings and Frobenius extensions. This establishes a one-to-one correspondence between Frobenius corings and extensions.
8 pages, LaTeX; uses xypic; Prop 2.9 replaced by a remark