On the continuity of the spectrum in certain Banach algebras

Citation
I. Feldman et N. Krupnik, On the continuity of the spectrum in certain Banach algebras, INTEG EQ OP, 38(3), 2000, pp. 284-301
Citations number
24
Categorie Soggetti
Mathematics
Journal title
INTEGRAL EQUATIONS AND OPERATOR THEORY
ISSN journal
0378620X → ACNP
Volume
38
Issue
3
Year of publication
2000
Pages
284 - 301
Database
ISI
SICI code
0378-620X(200011)38:3<284:OTCOTS>2.0.ZU;2-F
Abstract
In this paper we describe some classes of linear operators T is an element of L(H) (mainly Toeplitz, Wiener-Hopf and singular integral) on a Hilbert s paces H such that the spectrum sigma (T,L(H)) is continuous at the points T from these classes. We also describe some subalgebras A of the algebras (A ) over tilde for which the spectrum sigma (x, (A) over tilde) becomes conti nuous at the points x when sigma (x, (A) over tilde) is restricted to the s ubalgebra A. In particular, we show that the spectrum sigma (x, (A) over ti lde) is continuous in Banach algebras (A) over tilde with polynomial identi ties. Examples of such algebras are given. (1)