Timed Multiparty Session Types

We propose a typing theory, based on multiparty session types, for modular verification of real-time choreographic interactions. To model real-time implementations, we introduce a simple calculus with delays and a decidable static proof system. The proof system ensures type safety and time-error freedom, namely processes respect the prescribed timing and causalities between interactions. A decidable condition on timed global types guarantees time-progress for validated processes with delays, and gives a sound and complete characterisation of a new class of CTAs with general topologies that enjoys progress and liveness

Fast algorithms for handling diagonal constraints in timed automata

A popular method for solving reachability in timed automata proceeds by enumerating reachable sets of valuations represented as zones. A na\"ive enumeration of zones does not terminate. Various termination mechanisms have been studied over the years. Coming up with efficient termination mechanisms has been remarkably more challenging when the automaton has diagonal constraints in guards. In this paper, we propose a new termination mechanism for timed automata with diagonal constraints based on a new simulation relation between zones. Experiments with an implementation of this simulation show significant gains over existing methods.Comment: Shorter version of this article to appear in CAV 201

Timed vs. Time-triggered automata

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)3170340-35

Communicating Timed Automata: The More Synchronous, the More Difficult to Verify

We study channel systems whose behaviour (sending and receiving messages via unbounded FIFO channels) must follow given timing constraints specifying the execution speeds of the local components. We propose Communicating Timed Automata (CTA) to model such systems. The goal is to study the borderline between decidable and undecidable classes of channel systems in the timed setting. Our technical results include: (1) CTA with one channel without shared states in the form (A_1,A_2, c_1,2) is equivalent to one-counter machine, implying that verification problems such as checking state reachability and channel boundedness are decidable, and (2) CTA with two channels without sharing states in the form (A_1,A_2,A_3, c_1,2,c_2,3) has the power of Turing machines. Note that in the untimed setting, these systems are no more expressive than finite state machines. We show that the capability of synchronizing on time makes it substantially more difficult to verify channel systems

Timed automata can always be made implementable

Abstract. Timed automata follow a mathematical semantics, which assumes perfect precision and synchrony of clocks. Since this hypothesis does not hold in digital systems, properties proven formally on a timed automaton may be lost at implementation. In order to ensure implementability, several approaches have been considered, corresponding to different hypotheses on the implementation platform. We address two of these: A timed automaton is samplable if its semantics is preserved under a discretization of time; it is robust if its semantics is preserved when all timing constraints are relaxed by some small positive parameter. We propose a construction which makes timed automata implementable in the above sense: From any timed automato

Robustness in timed automata

In this paper we survey several approaches to the robustness of timed automata, that is, the ability of a system to resist to slight perturbations or errors. We will concentrate on robustness against timing errors which can be due to measuring errors, imprecise clocks, and unexpected runtime behaviors such as execution times that are longer or shorter than expected. We consider the perturbation model of guard enlargement and formulate several robust verification problems that have been studied recently, including robustness analysis, robust implementation, and robust control. © 2013 Springer-Verlag.SCOPUS: cp.kinfo:eu-repo/semantics/publishe