Timeline for First: upper-star, then: lower-star, finally: lower-shriek
Current License: CC BY-SA 2.5
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 12, 2010 at 2:34 | vote | accept | David Spivak | ||
| Sep 12, 2010 at 0:25 | answer | added | Todd Trimble | timeline score: 7 | |
| Sep 2, 2010 at 22:32 | comment | added | some guy on the street | edit: "the as" $\mapsto$ "as the" | |
| Sep 2, 2010 at 22:31 | comment | added | some guy on the street | After stewing on the implicit puzzle, I have to admit I don't see how to get down to three factors. Can you tell me if I seem to understand left/right pushouts well-enough if I say I'm using the as definition of Image "a coequalizer of a kernel pair"? As a bonus, you practically get the requested epic/monic factorization for free; but I think there are at least three extra pull-backs in my recipe. | |
| Aug 16, 2010 at 21:47 | comment | added | some guy on the street | Since there are three factors, I wonder if someone did/should check whether there's a prop/struct/stuff factorization (aka. Postnikov-Moore!) lurking about? | |
| Aug 14, 2010 at 6:16 | comment | added | Peter LeFanu Lumsdaine | Some very vague scraps of memory that might be relevant: polynomial functors can be seen as an internal cousin of familially representable functors. Fam. rep. functors have a nice characterisation as “preserving wide pullbacks” (Carboni/Johnstone). Iirc, there are some nice constructions making the analogy between poly. and fam. rep. functors concrete, and iirc there may have been an internal analogue of the “wide pullbacks” condition. Unfortunately I can't remember the details, or even where/from whom I heard this. I think they said it was from work by Joyal, perhaps? | |
| Aug 13, 2010 at 21:32 | comment | added | Andrew Stacey | +1 for the title alone! | |
| Aug 13, 2010 at 19:37 | history | asked | David Spivak | CC BY-SA 2.5 |