Cyclic homology arising from adjunctions

Niels Kowalzig, Ulrich Krähmer, and Paul Slevin

Given a monad and a comonad, one obtains a distributive law between them from lifts of one through an adjunction for the other. In particular, this yields for any bialgebroid the Yetter-Drinfel'd distributive law between the comonad given by a module coalgebra and the monad given by a comodule algebra. It is this self-dual setting that reproduces the cyclic homology of associative and of Hopf algebras in the monadic framework of Böhm and Stefan. In fact, their approach generates two duplicial objects and morphisms between them which are mutual inverses if and only if the duplicial objects are cyclic. A 2-categorical perspective on the process of twisting coefficients is provided and the role of the two notions of bimonad studied in the literature is clarified.

Keywords: cyclic homology, Hopf algebroids, Hopf monads, distributive laws

2010 MSC: 16T05, 18C15, 18C20, 19D55

Theory and Applications of Categories, Vol. 30, 2015, No. 32, pp 1067-1095.

Published 2015-08-04.

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