Preservation of the Unconditional Basis Property under Non-Self-Adjoint Perturbations of Self-Adjoint Operators

摘要

Let T be a self-adjoint operator on a Hilbert space H with domain D(T). Assume that the spectrum of T is contained in the union of disjoint intervals Delta(k) = [alpha(2k-1), alpha(2k)], k is an element of Z, the lengths of the gaps between which satisfy the inequalities