Evolution of the complex spectrum of a periodic operator
This article is concerned with the study of the structure of the spectrum of a periodic non-self-adjoint operator from the point of view of its evolution with respect to a parameter \(r\in [0, 1]\). For such an operator the definition of the spectrum reduces to the solution of the dispersion equation \(F(r, p, e^{i\theta})= 0\). The author proved that the spectrum just defined is symmetric with respect to the real axis. The article contains some more results.
structure of the spectrum of a periodic non-self-adjoint operator
scientific article; zbMATH DE number 484289