Timeline for Is Tannaka theory easy?
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 7, 2019 at 18:00 | answer | added | Ender Wiggins | timeline score: 1 | |
| Nov 30, 2019 at 13:57 | comment | added | fosco | @PhilTosteson do you have a reference to prove Barr-Beck theorem using coends? | |
| Nov 4, 2019 at 22:52 | comment | added | fosco | I guess that if you have an integral, everything seems a coend :) | |
| Nov 4, 2019 at 19:17 | comment | added | Noah Snyder | I think most people who learn Tannaka-Krein duality do not know Kan extensions, Barr-Beck, or "elementary coend calculus." Which isn't to say that this might not be a great approach, just that it's not easy for everyone. | |
| Oct 26, 2019 at 10:08 | comment | added | fosco | I agree! That's why we teach things the simple way as soon as we can. Is it the case of Tannaka here? | |
| Oct 26, 2019 at 2:07 | comment | added | Theo Johnson-Freyd | Just because something is easy now certainly doesn't make it easy half a century ago. | |
| Oct 25, 2019 at 15:24 | comment | added | Phil Tosteson | I think Tannakian reconstruction is a monoidal upgrade of the Barr-Beck theorem (wikipedia says that this was first observed by Deligne, and is now the standard approach). And Barr-Beck can be proved very easily using ingredients that are similar to the ones in your argument (which I haven't read carefully). So the answer is probably: yes, Tannaka duality is easy and should admit formal proofs using co-ends. | |
| Oct 25, 2019 at 15:03 | comment | added | Maxime Ramzi | Why is it essentially surjective on objects and full ? | |
| Oct 25, 2019 at 13:43 | history | asked | fosco | CC BY-SA 4.0 |