Games on Pushdown Graphs and Extensions

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar. Two player games are a standard model of reactive computation, where e.g. one player is the controller and the other is the environment. A game is won by a player if she has a winning strategy, i.e., if she can win every play. Given a finite description of the game, our aim is to compute the winner and a winning strategy. For finite graphs these problems have been solved for a long time, although some complexity questions remain open. We consider several classes of infinite graphs, from transition graphs of pushdown automata up to graphs of the Caucal hierarchy, and we investigate different winning conditions: reachability, recurrence (Büchi), parity, and the a called Σ3-condition. Two kinds of techniques are developed: a symbolic approach based on finite automata recognizing infinite sets of configurations and a game simulation which reduces a given game into a simpler one and solves it. Different kinds of strategie

Ein Virus testet den Wohlfahrtsstaat

This essay discusses some of the consequences of the widely observed resurgence of a strong interventionist state during the corona crisis. Its focus is on how health and welfare arrangements impact the elderly, the group primarily affected by COVID-19. Four related perspectives – viewing the crisis as a “natural experiment,” the relationship between experts and politics, biopolitical arguments, and age discrimination – are used to unpack the major inequalities, tensions and deficits in the social and sanitary policies of Western Europe and the US