Continuous-time Markov decision processes (CTMDPs) are widely used for the control of queueing systems, epidemic and manufacturing processes. Various results on optimal schedulers for discounted and average reward optimality criteria in CTMDPs are known, but the typical game-theoretic winning objectives have received scant attention so far. This paper studies various sorts of reachability objec...

We prove that on prefix-recognizable graphs reachability is complete for deterministic exponential time matching the complexity of alternating reachability.

Unbounded model checking of invariant properties is typically solved using symbolic reachability. However, BDD based reachability methods suffer from lack of robustness in performance, whereby it is difficult to estimate which one should be adopted for a given problem. We present a novel approach that examines a few short samples of the computation leading to an automatic, robust and modular wa...

This paper is about reachability analysis in a restricted subclass of multi-pushdown automata: we assume that the control states of an automaton are partially ordered, and all transitions of an automaton go downwards with respect to the order. We prove decidability of the reachability problem, and computability of the backward reachability set. As the main contribution, we identify relevant sub...

In a reachability-time game, players Min and Max choose moves so that the time to reach a final state in a timed automaton is minimised or maximised, respectively. Asarin and Maler showed decidability of reachability-time games on strongly non-Zeno timed automata using a value iteration algorithm. This paper complements their work by providing a strategy improvement algorithm for the problem. I...

Graph reachability is a fundamental problem in many applications, such as reasoning in lightweight formalisms, geographic navigation, XML/RDF/OWL query processing, etc. Many real world scenarios involve huge graphs and require fast algorithms to test for reachability between nodes. The problem becomes even more challenging when the graph is rapidly changing and received as a real-time stream of...

Branching VASS (BVASS) generalise vector addition systems with states by allowing for special branching transitions that can non-deterministically distribute a counter value between two control states. A run of a BVASS consequently becomes a tree, and reachability is to decide whether a given configuration is the root of a reachability tree. This paper shows P-completeness of reachability in BV...