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RESEARCH ARTICLE
Weak Frobenius monads and Frobenius bimodules
Robert Wisbauer Department of Mathematics, HHU, 40225 Düsseldorf, Germany
Аннотация:
As observed by Eilenberg and Moore (1965), for a monad
$F$ with right adjoint comonad
$G$ on any category
$\mathbb{A}$, the category of unital
$F$-modules
$\mathbb{A}_F$ is isomorphic to the category of counital
$G$-comodules
$\mathbb{A}^G$. The monad
$F$ is Frobenius provided we have
$F=G$ and then
$\mathbb{A}_F\simeq \mathbb{A}^F$. Here we investigate which kind of isomorphisms can be obtained for non-unital monads and non-counital comonads. For this we observe that the mentioned isomorphism is in fact an isomorphisms between
$\mathbb{A}_F$ and the category of bimodules
$\mathbb{A}^F_F$ subject to certain compatibility conditions (Frobenius bimodules). Eventually we obtain that for a weak monad
$(F,m,\eta)$ and a weak comonad
$(F,\delta,\varepsilon)$ satisfying $Fm\cdot \delta F = \delta \cdot m = mF\cdot F\delta$ and
$m\cdot F\eta = F\varepsilon\cdot \delta$, the category of compatible
$F$-modules is isomorphic to the category of compatible Frobenius bimodules and the category of compatible
$F$-comodules.
Ключевые слова:
pairing of functors, adjoint functors, weak (co)monads, Frobenius monads, firm modules, cofirm comodules, separability.
MSC: 18A40,
18C20,
16T1 Поступила в редакцию: 28.12.2015
Язык публикации: английский