The aim of this paper is to develop an analytical approach to obtain the sharp estimates for
the lowest positive periodic eigenvalue and all Dirichlet eigenvalues of a general Sturm …

Motivated by the study of certain nonlinear wave equations (in particular, the Camassa–
Holm equation), we introduce a new class of generalized indefinite strings associated with …

We describe an approach to universality limits for orthogonal polynomials on the real line
which is completely local and uses only the boundary behavior of the Weyl m-function at the …

Generalized indefinite strings provide a canonical model for self-adjoint operators with
simple spectrum (other classical models are Jacobi matrices, Krein strings and 2× 2 …

We extend the inverse spectral transform for the conservative Camassa-Holm flow on the
line to a class of initial data that requires strong decay at one endpoint but only mild …

Abstract We develop singular Weyl–Titchmarsh–Kodaira theory for one-dimensional Dirac
operators. In particular, we establish existence of a spectral transformation as well as local …

We introduce a dynamically defined class of unbounded, connected, equilateral metric
graphs on which the Kirchhoff Laplacian has zero Lebesgue measure spectrum and a non …

We derive necessary and sufficient conditions for universality limits for orthogonal
polynomials on the real line and related systems. One of our results is that the Christoffel …

In this paper, the class of (complex) quasi-Herglotz functions is introduced as the complex
vector space generated by the convex cone of ordinary Herglotz functions. We prove …

We derive a dispersion estimate for one-dimensional perturbed radial Schrödinger
operators. We also derive several new estimates for solutions of the underlying differential …