Rights statement: The final, definitive version of this article has been published in the Journal, Glasgow Mathematical Journal, 61 (3), pp 615-627 2004, © 2018 Cambridge University Press.
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - r-Fredholm theory in Banach algebras
AU - Benjamin, Ronalda
AU - Laustsen, Niels Jakob
AU - Mouton, Sonja
N1 - The final, definitive version of this article has been published in the Journal, Glasgow Mathematical Journal, 61 (3), pp 615-627 2004, © 2018 Cambridge University Press.
PY - 2019/9/1
Y1 - 2019/9/1
N2 - Harte (Mathematische Zeitschrift, 1982) initiated the study of Fredholm theory relative to a unital homomorphism T: A→B between unital Banach algebras A and B based on the following notions: an element a∈A is called Fredholm if 0 is not in the spectrum of Ta, while a is Weyl (Browder) if there exist (commuting) elements b and c in A with a = b+c such that 0 is not in the spectrum of b and c is in the null space of T. We introduce and investigate the concepts of r-Fredholm, r-Weyl and r-Browder elements, where 0 in these definitions is replaced by the spectral radii of a and b, respectively.
AB - Harte (Mathematische Zeitschrift, 1982) initiated the study of Fredholm theory relative to a unital homomorphism T: A→B between unital Banach algebras A and B based on the following notions: an element a∈A is called Fredholm if 0 is not in the spectrum of Ta, while a is Weyl (Browder) if there exist (commuting) elements b and c in A with a = b+c such that 0 is not in the spectrum of b and c is in the null space of T. We introduce and investigate the concepts of r-Fredholm, r-Weyl and r-Browder elements, where 0 in these definitions is replaced by the spectral radii of a and b, respectively.
KW - Fredholm, Weyl and Browder elements
KW - Spectral theory
KW - spectral radius
KW - holomorphic function calculus
U2 - 10.1017/S0017089518000393
DO - 10.1017/S0017089518000393
M3 - Journal article
VL - 61
SP - 615
EP - 627
JO - Glasgow Mathematical Journal
JF - Glasgow Mathematical Journal
SN - 0017-0895
IS - 3
ER -