Timed process algebras are useful tools for the specification and verification of real-time systems. We study the expressiveness of (classes of) these algebras which deal with temporal aspects of concurrent systems by following very different interpretations: durational actions versus durationless actions, absolute time versus relative time, timed functional behavior versus time and functional ...

Whereas partial order methods have proved their efficiency for the analysis of discrete-event systems, their application to timed systems remains a challenging research topic. Here, we design a verification algorithm for networks of timed automata with invariants. Based on the unfolding technique, our method produces a branching process as an acyclic Petri net extended with read arcs. These arc...

We introduce Timed Counter Systems, a new class of systems mixing clocks and counters. Such systems have an infinite state space, and their reachability problems are generally undecidable. By abstracting clock values with a Region Graph, we show the Counter Reachability Problem to be decidable for three subclasses : Timed VASS, Bounded Timed Counter Systems, and Reversal-Bounded Timed Counter S...

Timed automata as acceptors of languages of finite timed words form a very useful framework for the verification of safety properties of real-time systems. Many of the classical automata-theoretic decision problems are undecidable for timed automata, for instance the inclusion or the universality problem. In this paper we consider restrictions of these problems: universality for deterministic t...

Timed automata can be studied in not only a dense-time setting but also a discrete-time setting. The most common example of discrete-time semantics is the so called sampled semantics (i.e., discrete semantics with a xed time granularity "). In the real-time setting, the universality problem is known to be undecidable for timed automata. In this work, we study the universality question for the l...

A language for representing timed automata is introduced. Its semantics is deened in terms of timed automata. This language is complete in the sense that any timed automaton can be represented by a term in the language. We also deene a direct operational semantics for the language in terms of (timed) transition systems. This is proven to be equivalent (or, more precisely, timed bisimilar) to th...

The design and synthesis of asynchronous circuits is gaining importance in both the industrial and academic worlds. Timed circuits are a class of asynchronous circuits that incorporate explicit timing information in the specification. This information is used throughout the synthesis procedure to optimize the design. In order to synthesize a timed circuit, it is necessary to explore the timed s...

We study the equational theory of Timed CCS as proposed by Wang Yi in CONCUR’90. Common to Wang Yi’s paper, we particularly focus on a class of linearly-ordered time domains exemplified by the positive real or rational numbers. We show that, even when the set of basic actions is a singleton, there are parallel Timed CCS processes that do not have any sequential equivalent and thus improve on th...