On the semi-Browder spectrum
Volume 123 / 1997
Studia Mathematica 123 (1997), 1-13
DOI: 10.4064/sm-123-1-1-13
Abstract
An operator in a Banach space is called upper (lower) semi-Browder if it is upper (lower) semi-Fredholm and has a finite ascent (descent). We extend this notion to n-tuples of commuting operators and show that this notion defines a joint spectrum. Further we study relations between semi-Browder and (essentially) semiregular operators.
