The stability radius of an operator of Saphar type
Volume 113 / 1995
Studia Mathematica 113 (1995), 169-175
DOI: 10.4064/sm-113-2-169-175
Abstract
A bounded linear operator T on a complex Banach space X is called an operator of Saphar type if its kernel is contained in its generalized range $⋂_{n=1}^{∞} T^n(X)$ and T is relatively regular. For T of Saphar type we determine the supremum of all positive numbers δ such that T - λI is of Saphar type for |λ| < δ.
