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4 votes
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48 views

Bicategories in which the composition functors $\circ_{A, B, C}$ admit right adjoints

In Bénabou's 1967 Introduction to Bicategories, he mentions that, in a forthcoming part II, he would study bicategories $\mathcal K$ in which each composition functor $$\circ_{A, B, C} \colon \mathcal …
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2 votes
0 answers
13 views

Reference for the biequivalence between the bicategory of distributors and the bicategory of...

It is well known that a distributor/profunctor $A \not\rightarrow B$, i.e. a functor $B^{\text{op}} \times A \to \mathrm{Set}$, is equivalent to a two-sided discrete fibration from $A$ to $B$. Further …
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3 votes
0 answers
44 views

Lax morphism classifiers via lax-idempotentification

Let $T$ be a 2-monad on a nice 2-category $\mathcal K$, so that the inclusion $T\text{-}\mathbf{Alg}_s \to T\text{-}\mathbf{Alg}_l$ of the 2-category of (strict) $T$-algebras and strict $T$-algebra mo …
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2 votes
Accepted

If a monad in a 2-category admits a terminal resolution, does it admit an Eilenberg–Moore ob...

The answer is no: it is possible to have a terminal resolution without having an Eilenberg–Moore object. Consider the 2-category $\mathbf{DagCat}$ of dagger categories, dagger functors, and natural tr …
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3 votes
0 answers
52 views

Universal property of 2-presheaves and pseudo/lax/colax natural transformations

For each small 2-category $\mathscr K$, the 2-category $[\mathscr K^\circ, \mathrm{Cat}]$ of 2-functors and 2-natural transformations has a universal property: it is the free cocompletion of $\mathscr …
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5 votes
0 answers
83 views

Free cocompletion of a 2-category under pseudo colimits, lax colimits, and colax colimits

Let $\mathscr K$ be a small 2-category. It follows from $\mathrm{Cat}$-enriched category theory that the free cocompletion of $\mathscr K$ under strict 2-colimits of 2-functors is given by the 2-categ …
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6 votes
0 answers
93 views

Example of a pseudomonad on Cat whose pseudoalgebras are not the pseudoalgebras for a 2-monad

For every pseudomonad $T$ on the 2-category of (locally small) categories $\mathbf{Cat}$, we can consider the 2-category of $T$-pseudoalgebras and pseudomorphisms $T\text{-PsAlg}_p$, which is equipped …
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4 votes

Adjoining extensions in bicategories

A partial answer is contained in Betti's Formal theory of internal categories (page 49), where he states that the bicategory $\mathbf{Dist}(\mathcal E)$ of $\mathcal E$-internal distributors is the fr …
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5 votes
1 answer
280 views

3-functoriality of the lax Gray tensor product

In Formal category theory: adjointness for 2-categories, Gray defines a tensor product of 2-categories, now more commonly known as the lax Gray tensor product, which I will denote by $\otimes_l$. For …
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6 votes

What are the internal adjunctions in the bicategory $\mathsf{Span}$?

Let $\mathcal E$ be a category with pullbacks. A span $A \xleftarrow a X \xrightarrow b B$ has a right adjoint in the bicategory $\mathbf{Span}(\mathcal E)$ if and only if $a$ is invertible in $\mathc …
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9 votes
0 answers
102 views

Adjoining a morphism to a finitely complete category

Let $\mathscr C$ be a finitely complete category. Let $x, y$ be objects of $\mathscr C$. We can describe the universal property of freely adjoining a morphism $x \to y$ to $\mathscr C$: it comprises a …
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2 votes

Pseudofunctors of 2-variables and Gray tensor product of bicategories

Since this question was written, there is a paper 2-dimensional bifunctor theorems and distributive laws by Faul–Manuell–Siqueira based on this idea. In particular, they prove a "bifunctor theorem" fo …
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2 votes

Reference request for facts about bi(co)descent objects

This follows from Lemma 2.3 and Proposition 3.2 of Creurer–Marmolejo–Vitale's Beck's theorem for pseudo-monads, together with fact that the bicategorical Yoneda embedding preserves bilimits. Presumab …
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1 vote
Accepted

Morphism of pseudomonads induces pullback functors between pseudoalgebras

Yes, Theorem 3.4 of Gambino–Lobbia's On the formal theory of pseudomonads and pseudodistributive laws establishes that pseudomonad morphisms are in correspondence with liftings to pseudoalgebras. They …
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9 votes
0 answers
127 views

Is totality a (large) cocompleteness condition?

A locally small category $A$ is called total if its Yoneda embedding $A \to [A^\circ, \mathbf{Set}]$ has a left adjoint. Such categories are necessarily small-cocomplete (since the presheaf category …
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