Abstract The indefinite Sturm-Liouville operator A=(sgnx)(− d2/dx2+ q (x)) is studied. It is
proved that similarity of A to a selfadjoint operator is equivalent to integral estimates of …

We consider a singular Sturm—Liouville expression with the indefinite weight sgn x. There is
a self-adjoint operator in some Krein space associated naturally with this expression. We …

On the spectral theory of singular indefinite Sturm–Liouville operators Page 1 J. Math. Anal.
Appl. 334 (2007) 1439–1449 www.elsevier.com/locate/jmaa On the spectral theory of singular …

We present a new necessary condition for similarity of indefinite Sturm–Liouville operators to
self-adjoint operators. This condition is formulated in terms of Weyl–Titchmarsh-\frac …

We investigate some classes of eigenvalue dependent boundary value problems of the form
where A⊂ A+ is a symmetric operator or relation in a Krein space K, τ is a matrix function …

Eigenvalues in the essential spectrum of a weighted Sturm-Liouville operator are studied
under the assumption that the weight function has one turning point. An abstract approach to …

The indefinite Sturm-Liouville operator A=(sgn x)(− d2/dx2+ q) is studied. It is proved that
similarity of A to a selfadjoint operator is equivalent to integral estimates of Cauchy type …

The indefinite Sturm-Liouville operator $ A=(\sgn x)(-d^ 2/dx^ 2+ q (x)) $ is studied. It is
proved that similarity of $ A $ to a selfadjoint operator is equivalent to integral estimates of …