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3 votes
1 answer
133 views

Is there a non-symmetric monoidal monad?

Recall that a monoidal monad on a monoidal category $(\mathcal{C}, \otimes, I)$ is a monad $(M, \eta, \mu)$ on $\mathcal{C}$ such that $M$ is also equipped with the structure of a lax monoidal functor ...
Naïm Favier's user avatar
  • 3,550
3 votes
1 answer
108 views

Cocommutative bimonads: Why does this diagram commute?

1. Definitions Let $(C, \otimes,I, a, l,r,c)$ be a monoidal category with braiding $c:\otimes \rightarrow\otimes ^{op}$. Let $(S,\mu,\eta,\tau,\theta)$ be a bimonad on $C$. Following Turaev and ...
Max Demirdilek's user avatar
1 vote
1 answer
419 views

What makes every strong monad on a certain category be a monoidal functor?

A concept named Monad is used a lot in functional programming. And in spite their definition is not completely same with the definition of monad in category theory, as I know, Monad on a programming ...
Antel's user avatar
  • 13
2 votes
0 answers
83 views

Effectus theory and the Giry monad

Is the Kleisli category of the Giry monad a monoidal effectus with copiers, in the sense of Definition 70 from An Introduction to Effectus Theory ? The fact that this category is an effectus is ...
Richard Southwell's user avatar
5 votes
2 answers
180 views

Recover the monoidal structure on $\mathbb{Ab}$ from the monad over Set

The category of abelian groups $\mathbb{Ab}$ has a monoidal (closed) structure $(\otimes, \mathbb{Z})$. Moreover, it is monadic over the category of sets via the free abelian group monad $$\mathbb{Z}[\...
Ivan Di Liberti's user avatar
0 votes
0 answers
171 views

Elements of the Monoid in the category of endofunctors

Quoting from Categories for the Working Mathematician by Saunders Mac Lane: All told, a monad in X is just a monoid in the category of endofunctors of X, with product × replaced by composition of ...
Roland's user avatar
  • 337
7 votes
1 answer
361 views

Monoid in the category of endofunctors and Monoid as a category with one object

Quoting from Categories for the Working Mathematician by Saunders Mac Lane: All told, a monad in X is just a monoid in the category of endofunctors of X, with product × replaced by composition of ...
Roland's user avatar
  • 337
5 votes
0 answers
237 views

Monads, monoidal categories

I'm interested in learning about monads and their relations to algebraic structures (as a generalization of universal algebra, if I understand well -correct me if not) . In the process of learning ...
Maxime Ramzi's user avatar
  • 44.4k
3 votes
1 answer
132 views

2-monad and 2-operad of monoidal categories, explicit construction

It is well-known that monoids are algebras for the free monoid monad, and can be seen as well as algebras for the associative operad. Less known is the categorified statement: for example, monoidal ...
geodude's user avatar
  • 8,307
15 votes
1 answer
2k views

Details in applying the Barr-Beck monadicity theorem to Tannakian reconstruction

The Barr-Beck monadicity theorem gives necessary and sufficient conditions for a category $\mathcal{C}$ to be equivalent to a category of (co)algebras over a (co)monad. A functor $F:\mathcal{C}\to\...
Alex Saad's user avatar
  • 3,619
5 votes
1 answer
129 views

Algebras for monads in Cat and 2-categories

An algebra for a monad $(T, \mu, \eta)$ on a category $\mathbb{C}$ is defined as a morphism $T X \to X$ for some object $X$ such that the obvious diagrams commute. If I look at the monad as a monoid ...
eefzkj's user avatar
  • 270
17 votes
3 answers
1k views

Theory of promonads

I'm led to define a promonad in $\bf D$ as a monoid in the category of endo-profunctors of a category $\bf D$, where the product of two profunctors is their composition as profunctors: $$ F\odot G := \...
fosco's user avatar
  • 12.2k