2 papers
math.SP2026
The direct spectral problem for indefinite canonical systems
Matthias Langer, Harald Woracek
For indefinite (Pontryagin space) canonical systems that contain an inner singularity we prove the existence of generalised boundary values at the singularity, which are used to fo…
math.SP2025
Spectral properties of canonical systems: discreteness and distribution of eigenvalues
Jakob Reiffenstein, Harald Woracek
In this survey paper we review classical results and recent progress about a certain topic in the spectral theory of two-dimensional canonical systems. Namely, we consider the ques…