Banach elements and spectrum in Banach quasi *-algebras
- Autori: TRAPANI, C
- Anno di pubblicazione: 2006
- Tipologia: Articolo in rivista
- Parole Chiave: bounded elements, normed quasi *-algebras
- OA Link: http://hdl.handle.net/10447/23358
Abstract
A normal Banach quasi -algebra (X;A_0) has a distinguished Banach - algebra X_b consisting of bounded elements of X. The latter -algebra is shown to coincide with the set of elements of X having fi nite spectral radius. If the family P(X) of bounded invariant positive sesquilinear forms on X contains suffi ciently many elements then the Banach -algebra of bounded elements can be characterized via a C -seminorm defi ned by the elements of P(X).