Timeline for Subalgebra of a group algebra
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 19, 2019 at 5:29 | comment | added | John Palmieri | @JoshuaGrochow: Ravenel uses his version to show that a particular Hopf algebra is a group algebra, so he found it useful. | |
| Apr 19, 2019 at 5:28 | comment | added | John Palmieri | Ravenel's book is available from his web page: web.math.rochester.edu/people/faculty/doug/mybooks/ravenel.pdf. He is certainly working in positive characteristic, but I don't know if this is necessary for his condition. He is certainly working with Hopf algebras, since otherwise there wouldn't be a multiplication on the dual. | |
| Apr 19, 2019 at 2:08 | comment | added | Joshua Grochow | While these are interesting characterizations, I wonder whether checking for such special bases is any easier than just looking for a group basis directly? (by which I mean a basis of A which is closed under multiplication and consists of units) it may very well be, I just don't see either way yet. | |
| Apr 19, 2019 at 0:04 | comment | added | Student | For Ravenel's statement, I do not have access to the book for now. Would you mind pointing it out that in his content, is $A$ assumed to be a Hopf algebra? | |
| Apr 19, 2019 at 0:03 | comment | added | Student | Great! Also, I think Sweedler provided a fairly nice answer already, since if A comes from some subgroup, then A is automatically a sub-Hopf-algebra! | |
| Apr 18, 2019 at 22:29 | comment | added | AHusain | Is there a characteristic assumption on the last part? Is there division by 2 in formula for y? | |
| Apr 18, 2019 at 22:23 | history | answered | John Palmieri | CC BY-SA 4.0 |