Abstractions for the local-time semantics of timed automata: a foundation for partial-order methods

Abstract

A timed network is a parallel composition of timed automata synchronizing on common actions. We develop a methodology that allows to use partial-order methods when solving the reachability problem for timed networks. It is based on a local-time semantics proposed by [Bengtsson et al. 1998].A new simulation based abstraction of local-time zones is proposed. The main technical contribution is an efficient algorithm for testing subsumption with respect to this abstraction operator. The abstraction is not finite for all networks. It turns out that, under relatively mild conditions, there is no finite abstraction for local-time zones that works for arbitrary timed networks. To circumvent this problem, we introduce a notion of a bounded-spread network. The spread of a network is a parameter that says how far the local times of individual processes need to diverge. For bounded-spread networks, we show that it is possible to use subsumption and partial-order methods at the same time.

Broadcast Propagation Time in SpaceFibre Networks with Various Types of Spatial Redundancy

“…This technique was developed for verification and analysis of the characteristics of systems with real-time requirements [2][3][4]. Special variables (timers or clocks) are used to add the notion of time to formal models [5,6]. Timed automata could also include variables of other types.…”

“…Such transitions can be used to synchronize individual timed automata in the network. If the transition is asynchronous, the reading of the event from the channel can be delayed in relation to the moment when the event is written to the channel [15][16][17][18]. In this paper, we propose an approach based on the networks built upon the timed automata to dynamically analyze broadcast transmission characteristics.…”