On a class of perturbed operators
Let \(A(\varepsilon)=B_0 -\varepsilon B\), where \(B_0\) and \(B\) are given linear operators in Hilbert space. The author establishes some sufficient conditions for eigenvalues and corresponding eigenvectors of \(A(\varepsilon)\) to be analytic functions of \(\varepsilon\) at \(\varepsilon =0\), and applies the result to a certain (nonselfadjoint) functional-differential operator.
perturbation of eigenvalues and eigenvectors
scientific article; zbMATH DE number 1541502