Timeline for Restricting a continuous positive-semidefinite function to a finite subset
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 20, 2016 at 14:31 | comment | added | Yemon Choi | Not that I know of... | |
| Sep 20, 2016 at 14:26 | comment | added | Mikael de la Salle | I have often wondered: is there any connection between you and Choi (M-D)? | |
| Sep 20, 2016 at 14:24 | comment | added | Yemon Choi | I often feel that Choi (Y) needs to pay closer attention to ideas introduced by Choi (M-D) | |
| Sep 20, 2016 at 11:09 | comment | added | Mikael de la Salle | @YemonChoi: sure. $f \colon G \to \mathbf{C}$ being PSD means that the Fourier multiplier $M_f$ with symbol $f$ is completely positive. So if we have such PSD $f$ and $t \in G$ such that $f(t) = f(0)=1$, we have (Choi) that $t$ belongs to the multiplicative domain of $M_f$, and so the whole group generated by $f$ belongs to the multiplicative domain, ie that $f$ is constant equal to $1$ on the group generated by $t$. | |
| Sep 19, 2016 at 13:53 | vote | accept | Yemon Choi | ||
| Sep 19, 2016 at 13:53 | comment | added | Yemon Choi | Nice! I wonder if this example can be seen as some kind of argument with multiplicative domains or the Schwarz inequality for cp maps... but this is purely idle speculation | |
| Sep 19, 2016 at 8:27 | history | answered | Mikael de la Salle | CC BY-SA 3.0 |