This work focuses on the contemporary developments and results in mathematical systems theory and control. The book is written in honour of Diederich Hinrichsen, for his fundamental contributions and achievements in the fields of linear systems theory and control theory, and for his long-term achievements in estabilshing mathematical systems theory in Germany. A key theme of the book is the stability and robustness of linear and nonlinear systems using the concepts of stability radii and spectral value sets. Chapters survey advances in linear and nonlinear systems theory, including parametrizations, problems and behaviours of linear systems, convolutional codes, and complementary and hybrid systems. In addition, the volume examines controllability and stabilization of infinite dimensional systems (allowing for hysteresis nonlinearities) with functional analytic and algebraic approaches.