Ordinary and partial differential operators with an indefinite weight function can be viewed
as bounded perturbations of non-negative operators in Krein spaces. Under the assumption …

Non-real eigenvalues of indefinite Sturm–Liouville problems - ScienceDirect Skip to main
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Non-real eigenvalues of indefinite SturmÖLiouville problems Page 1 J. Spectr. Theory 4 (2014),
53–63 DOI 10.4171/JST/61 Journal of Spectral Theory © European Mathematical Society A priori …

The present paper gives a priori upper and lower bounds on non-real eigenvalues of regular
indefinite Sturm-Liouville problems only under the integrability conditions. More generally, a …

The non-real spectrum of a singular indefinite Sturm–Liouville operator A= 1 r (− ddxpdd x+
q) with a sign changing weight function r consists (under suitable additional assumptions on …

Bounds on real and imaginary parts of non-real eigenvalues of a non-definite Sturm–Liouville
problem - ScienceDirect Skip to main contentSkip to article Elsevier logo Journals & Books …

We study particular cases of left-definite eigenvalue problems A ψ= B ψ A ψ\;=\; B ψ, with
A≥ 𝜀 IA\; ≧\; ε I for some 𝜀> 0 and B self− adjoint ε\;>\; 0\; and\; B\; self-adjoint, but B not …

Abstract We study singular Sturm–Liouville operators of the form 1 rj (− ddxpjdd x+ qj), j= 0,
1, in L 2 ((a, b); rj) with endpoints a and b in the limit point case, where, in contrast to the …

The spectrum of the singular indefinite Sturm-Liouville operator\begin {equation*}
A=\operatorname {sgn}(\cdot)\bigl (-\tfrac {d^ 2}{dx^ 2}+ q\bigr)\end {equation*} with a real …

In this paper we develop a perturbation approach to investigate spectral problems for
singular ordinary differential operators with indefinite weight functions. We prove a general …