Rank One Perturbations, Approximations, and Selfadjoint Extensions

Rank One Perturbations, Approximations, and Selfadjoint Extensions

of a semibounded selfadjoint operator A are studied with the help of distribution theory. It is shown that such perturbations can be defined for finite values of : even if the element . does not belong to H&1(A). Approximations of the rank one perturbations are constructed in the strong operator topology. It is proven that rank one H&2 perturbations can be defined uniquely for the homogeneous o...

Perturbation theory of selfadjoint matrices and sign characteristics under generic structured rank one perturbations∗

For selfadjoint matrices in an indefinite inner product, possible canonical forms are identified that arise when the matrix is subjected to a selfadjoint generic rank one perturbation. Genericity is understood in the sense of algebraic geometry. Special attention is paid to the perturbation behavior of the sign characteristic. Typically, under such a perturbation, for every given eigenvalue, th...

Rank one perturbations of self-adjoint operators

Rank One Perturbations with Infinitesimal Coupling

We consider a positive self-adjoint operator A and formal rank one pertubrations

Bounded Rank-one Perturbations in Sampling Theory

Sampling theory concerns the problem of reconstruction of functions from the knowledge of their values at some discrete set of points. In this paper we derive an orthogonal sampling theory and associated Lagrange interpolation formulae from a family of bounded rank-one perturbations of a self-adjoint operator that has only discrete spectrum of multiplicity one. Mathematics Subject Classificatio...