Timeline for Banach algebra $A$ without an approximate identity but $A^2=A$
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 23, 2019 at 16:11 | vote | accept | Fermat | ||
| Feb 23, 2019 at 14:58 | comment | added | YCor | ... or just the direct product of $A$ or $B$ above, with your favorite unital infinite-dimensional Banach algebra. | |
| Feb 23, 2019 at 14:03 | comment | added | YCor | Fix a Euclidean norm on $A$ for which $\|ab\|\le\|a\|\|b\|$ for all $a\in A$ (restricted direct product), consider $\bigoplus_{n\in\mathbf{N}}A$, and complete to a Hilbertian norm. | |
| Feb 23, 2019 at 13:44 | comment | added | Fermat | Thank you and what about infinite dimensional Banach algebras? Is there any? | |
| Feb 23, 2019 at 11:53 | history | answered | YCor | CC BY-SA 4.0 |