The Weyl’s Theorem and Its Perturbations in Semisimple Banach Algebra

Generalized Drazin-Riesz invertible elements in a semi-simple Banach algebra

“…The Browder resolvent set of an element a ∈ B related to a Banach subalgebra B of A is ρ b,B (a) = C \ σ b,B (a). Following [19,Theorem 3.9], an element a ∈ A is Browder if and only if a ∈ Φ A and 0 / ∈ acc σ(a). Then σ b (a) = σ e (a) ∪ acc σ(a).…”