On the stability of the Bishop's property($β$) under compact perturbations
Salah Mecheri
TL;DR
The paper addresses whether local spectral properties such as Bishop's property $β$, the decomposition property $δ$, and decomposability are preserved under sums and products of commuting operators. It introduces the Helton class $Helton_k(R)$ and leverages it to prove that $β$ is preserved under commuting perturbations $S$ with $S∈Helton_k(R)$, and that $T+K$ preserves $β$ when $K$ is algebraic and commutes with $T$, which in turn yields preservation of $δ$ for decomposable operators. The results further show that decomposable operators are stable under commuting perturbations of type quasinilpotent, compact, or algebraic, with corollaries extending to 2×2 operator matrices and analytic functional calculus. Overall, the findings establish broad stability of these local spectral properties under natural perturbations, strengthening the understanding of operator perturbations in local spectral theory.
Abstract
Let $B(X)$ be the Banach algebra of all bounded linear operators acting on a Banach space $X$. Are sums and products of commuting decomposable operators on Banach spaces decomposable? This is one of the most important open problems in the local spectral theory of operators on Banach spaces. Similarly, it is not known if local spectral properties such as the single valued extension property, Dunfords property $(C)$, Bishops property $(β)$, or the decomposition property ($δ$) are preserved under sums and products of commuting operators. But it is shown by Bourhim and Muller that the single-valued extension property is not preserved under the sums and products of commuting operators. On the positive side, Sun proved that the sum and the product of two commuting operators with Dunfords property $(C)$ have the single-valued extension property. Very recently, Aiena and Muller showed that the (localized) single-valued extension property is stable under commuting Riesz perturbations. In this paper, we show that Bishops property ($β$), the decomposition property ($δ$), or decomposable operators $T\in B(X)$ are stable under quasinilpotent, compact, and algebraic commuting perturbations.