Andreas Bärmann develops novel approaches for the solution of network design problems as they
arise in various contexts of applied optimization. At the example of an optimal expansion of
the German railway network until 2030 the author derives a tailor-made decomposition technique
for multi-period network design problems. Next he develops a general framework for the
solution of network design problems via aggregation of the underlying graph structure. This
approach is shown to save much computation time as compared to standard techniques. Finally
the author devises a modelling framework for the approximation of the robust counterpart under
ellipsoidal uncertainty an often-studied case in the literature. Each of these three
approaches opens up a fascinating branch of research which promises a better theoretical
understanding of the problem and an increasing range of solvable application settings at the
same time.
