This article studies a large class of two-player perfect-information turn-based parity games on infinite graphs, namely, those generated by collapsible pushdown automata. The main motivation for studying these comes from the connections automata and higher-order recursion schemes, both models being equi-expressive generating trees. Our result is to establish decidability such provide an effecti...

In this thesis we deal with games over infinite graphs with regular winning conditions. A well studied family of such games are the pushdown games. An important result for these games is that the winning region can be described by regular sets of configurations. We extend this result to games defined by higher-order pushdown systems. The higher-order pushdown systems extend the usual pushdown s...

When implementing recursive programs on a standard von Neumann random access machine (RAM) it is natural and well known how to use a pushdown store in order to keep track of the recursive procedure calls when the program runs. The more abstract world of program schemes abounds with examples of this pushdown – recursion relation. As a concrete example it is well known how to implement monadic re...

We introduce discrete pushdown timed automata that are timed automata with integer-valued clocks augmented with a pushdown stack. A connguration of a discrete pushdown timed automaton includes a control state, nitely many clock values and a stack word. Using a pure automata-theoretic approach, we show that the binary reachability (i.e., the set of all pairs of conngurations (;), encoded as stri...

In Hartmanis (1980) a simple proof is given of the fact (originally proved in Valiant (1976)) that the relative succinctness of representing deterministic context-free languages by deterministic vs. nondeterministic pushdown automata is not recursively bounded, in the following sense: there is no recursive function which, for deterministic context-free languages L, can bound the size of the min...