Abstract
We show that a Banach space X is isomorphic to a Hilbert space if and only if the trigonometric system is unconditional in L2 (II, X). If the unconditionally constant is equal to one then X is even isometric to a Hilbert space.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 233-240 |
| Number of pages | 8 |
| Journal | Mathematische Nachrichten |
| Volume | 158 |
| Issue number | 1 |
| DOIs | |
| State | Published - 1992 |
| Externally published | Yes |
ASJC Scopus subject areas
- General Mathematics