Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 2362
2 votes
Accepted

Intuition behind $\lambda$-pure subobjects

Think of the category of structures in some signature $\Sigma$. The functor represented by a finitely presentable object $F$, say, corresponds to some term in the language generated by $\Sigma$. For e …
Tim Campion's user avatar
  • 63.9k
4 votes

In a locally presentable category, is every object (a retract of) the colimit of a chain of ...

Since this result is derived by Lieberman, Rosicky, and Vasey as a corollary of some more sophisticated constructions with more sophisticated goals, I think it might be worth "compiling out" the proof …
3 votes

Example: Accessible category without colimits

Here's a general way to get an accessible category that likely will not have many colimits: let $C$ be a locally presentable category, and then let $C^{mono}$ be the category with the same objects as …
Tim Campion's user avatar
  • 63.9k
9 votes
Accepted

What are the reflective subcategories of the category of presentable categories?

Some ideas, building off of Simon Henry and Ivan di Liberti's remarks: $Pr^L$ is in fact essentially a large (not huge) category (in either the ordinary or $\infty$ context). That is, let $\lambda$ …
Tim Campion's user avatar
  • 63.9k
2 votes
Accepted

If $\mathcal C$ is a $\kappa$-accessible $\infty$-category, then is $Mor \mathcal C$ $\kappa...

Marc Hoyois answered in the comments: the answer is affirmative, by HTT 5.3.5.15.
2 votes

When is the homotopy category of an accessible $\infty$-category accessible?

Here's a further generalization: Claim: Let $\mathcal T$ be a triangulated category and with a $t$-structure such that $\mathcal T^\heartsuit$ is has coproducts, which are exact. Suppose there exi …
Tim Campion's user avatar
  • 63.9k
2 votes

When is the homotopy category of an accessible $\infty$-category accessible?

Here's something we can say which addresses a large class of examples. Let us say that a (possibly noncommutative) ring $R$ is not zero-dimensional if there exists $r \in R$ which is neither a right u …
Tim Campion's user avatar
  • 63.9k
4 votes
Accepted

Is every limit-closed, accessibly-embedded full subcategory of a presentable $\infty$-catego...

A few years later, this is proven, by Ragimov and Schlank.
Tim Campion's user avatar
  • 63.9k