Timed automata were introduced by Alur and Dill in the early 1990s and have since become the most prominent modelling formalism for real-time systems. A fundamental limit to the algorithmic analysis of timed automata, however, results from the undecidability of the universality problem: does a given timed automaton accept every timed word? As a result, much research has focussed on attempting t...

We study the complexity of identifying (learning) timed automata in the limit from data. Timed automata are finite state models that model time explicitly, i.e., using numbers. Because timed automata use numbers to represent time, they can be exponentially more compact than models that model time implicitly, i.e., using states. We show three results that are essential in order to exactly determ...

Timed and hybrid automata are extensions of finite-state machines for formal modeling of embedded systems with both discrete and continuous components. Reachability problems for these automata are well studied and have been implemented in verification tools. In this paper, for the purpose of effective error reporting and testing, we consider the membership problems for such automata. We conside...

We investigate extensions of Alur and Dill’s timed automata, based on the possibility to update the clocks in a more elaborate way than simply reset them to zero. We call these automata updatable timed automata. They form an undecidable class of models, in the sense that emptiness checking is not decidable. However, using an extension of the region graph construction, we exhibit interesting dec...

This deliverable describes the results of the QUASIMODO project on modelling quantitative system aspects. Keyword list: AADL, Arcade, architectural dependability evaluation, cost-bounded reachability, priced priced/weighted timed automata, probabilistic timed automata, probabilistic timed automata, probabilistic hybrid systems. ICT-FP7-STREP-214755 / QUASIMODO Page 2 of 12 Public

We study two questions in the theory of timed automata concerning timed language inclusion of real-time programs modeled as timed pushdown automata in real-time specifications with just one clock. We show that if the specification B is modeled as a timed automaton with one clock, then the language inclusion problem L(A) ⊆ L(B) for a timed pushdown automaton A is decidable. On the other hand, we...

In this paper we integrate two diierent approaches for the speciication and veriication of timed systems being used in control theory and computer science. These are the timed condition/event systems and the timed automata formalisms. Our main result states that timed condition/event systems can be eeciently transformed into timed automata which then can be analyzed automatically.

This paper proposes a new timed model named nested timed automata (NeTAs). An NeTA is a pushdown system whose stack symbols are timed automata (TAs). It either behaves as the top TA in the stack, or switches from one TA to another by pushing, popping, or changing the top TA of the stack. Different from existing component-based context-switch models such as recursive timed automata and timed rec...

We consider pushdown timed automata (PTAs) that are timed automata (with dense clocks) augmented with a pushdown stack. A configuration of a PTA includes a state, dense clock values and a stack word. By using the pattern technique, we give a decidable characterization of the binary reachability (i.e., the set of all pairs of configurations such that one can reach the other) of a PTA. Since a ti...

This chapter surveys timed automata as a formalism for model checking real-time systems. We begin with introducing the model, as an extension of finite-state automata with real-valued variables for measuring time. We then present the main model-checking results in this framework, and give a hint about some recent extensions (namely weighted timed automata and timed games).