Hopf-cyclic homology with contramodule coefficients
arXiv:0806.0389
Abstract
A new class of coefficients for the Hopf-cyclic homology of module algebras and coalgebras is introduced. These coefficients, termed stable anti-Yetter-Drinfeld contramodules, are both modules and contramodules of a Hopf algebra that satisfy certain compatibility conditions.
8 pages; misprints in the definition of t_n and calculations involving t_n on page 4 are corrected