Relating time progress and deadlines in hybrid systems

Supporting UML-based development of embedded systems by formal techniques

“…In order to fully verify the properties without this nonconservative assumption, we have used the redesigned model presented in Sect. 4.…”

“…This state machine uses interval conditions on clocks to model the nondeterminism introduced by the starting time and by jitter. All transitions here are interpreted as delayable according to the terminology of timed automata with urgency [4], meaning that once they are enabled, they will be taken before their time guard becomes false (unless they are disabled by some other discrete transition). Together with usual non-Zenoness assumption, this guarantees in this example that the computation cannot get stalled in any state.…”

“…Next, in Sect. 4 we redesign the considered part of the case study, to facilitate compositional techniques and abstraction, and apply the OMEGA techniques to this new model. An evaluation of the specification and verification experiments is presented in Sect.…”

A semantics of communicating reactive objects with timing

“…For instance, in Uppaal [16] clock invariants on locations are used to block delay steps and to ensure that certain transitions will be taken. In our current semantics we decided not to use invariants, but an urgency predicate on transitions; this is a special case of the timed automata with deadlines of [3]. Our motivation for this choice is that the condition for the progress of time is less complicated if we work with urgency of transitions.…”

“…Our timing extension is based on classical timed automata [1], but unlike e.g. Uppaal [16] we do not use invariants but an urgency predicate which is a restricted version of the timed automata with deadlines of [3]. A more high-level syntax for UML with real-time annotations, as developed in the Omega project, can be found in [6].…”