nLab
Kleisli category of a comonad

Contents

Context

2-Category theory

[[!include 2-category theory - contents]]

Higher algebra

[[!include higher algebra - contents]]

Contents

Idea

Formally dually to how a monad has a Kleisli category so also a comonad P:π’žβ†’π’žP \colon \mathcal{C}\to\mathcal{C} has a (co-)Kleisli category: its objects are the objects of π’ž\mathcal{C}, a morphism f:c 1β†’c 2f \colon c_1 \to c_2 in the co-Kleisli category is a morphism

f˜:P(c 1)⟢c 2 \tilde f \colon P(c_1) \longrightarrow c_2

in π’ž\mathcal{C}, and the composition of two such in the co-Kleisli category is represented by the morphism in π’ž\mathcal{C} given by

f 2∘f 1˜:P(c 1)⟢P(P(c 1))⟢P(f˜ 1)P(c 2)⟢f˜ 2c 3. \widetilde{f_2 \circ f_1} \colon P(c_1) \longrightarrow P(P(c_1)) \stackrel{P(\tilde f_1)}{\longrightarrow} P(c_2) \stackrel{\tilde f_2}{\longrightarrow} c_3 \,.

Examples

Last revised on September 22, 2017 at 16:10:02. See the history of this page for a list of all contributions to it.