Formal Modeling and Analysis of Timed Systems
Control and analysis of the timing of computations are crucial to many domains of system engineering, be it, e.g., for ensuring a timely response to stimuli originating in an uncooperative environment or for synchronizing components in VLSI. Reflecting this broad scope, timing aspects of systems from a variety of domains have been treated independently by different communities in computer science and control. Researchers interested in semantics, verification, and performance analysis study models such as timed automata and timed Petri nets, the digital design community focuses on propagation and switching delays, while designers of embedded controllers have to take account of the time taken by controllers to compute their responses after sampling the environment, as well as of the dynamics of the controlled process during this span. Timing-related questions in these separate disciplines have their particularities. However, there is growing awareness that there are basic problems that are common to all of them. In particular, all these subdisciplines treat systems whose behavior depends upon combinations of logical and temporal constraints; namely, constraints on the temporal distances between occurrences of events. Often, these constraints cannot be separated, as intrinsic dynamics of processes couples them, necessitating models, methods, and tools facilitating their combined analysis. Reflecting this fact, the aim of FORMATS is to promote the study of fundamental and practical aspects of timed systems, and to bring together researchers from different disciplines that share interests in modeling and analysis of timed systems and, as a generalization, hybrid systems. Typical topics include (but are not limited to): – Foundations and Semantics: Theoretical foundations of timed systems and languages; comparison between different models (such as timed automata, timed Petri nets, hybrid automata, timed process algebra, max-plus algebra, probabilistic models) – Methods and Tools: Techniques, algorithms, data structures, and software tools for analyzing or synthesizing timed or hybrid systems and for resolving temporal constraints (e.g., scheduling, worst-case execution time analysis, optimization, model checking, testing, constraint solving) – Applications: Adaptation and specialization of timing technology in application domains in which timing plays an important role (real-time software, embedded control, hardware circuits, and problems of scheduling in manufacturing and telecommunication, etc.)
The nested Petri nets are a nets-within-nets formalism convenient for modelling systems that consist of distributed mobile agents with individual behaviour. The formalism is supported by developed verification methods based on structural analysis and model checking techniques. Time constraints are crucial for many safety critical and everyday IoT systems. Recently, the non Turing-complete time semantics for Time Petri nets based on restricted urgency was suggested; and, it was shown that some behavioural analysis problems are decidable under the semantics. In the paper, the semantics is extended to the nested Petri nets formalism and it was demonstrated that some behavioural analysis problems are still decidable. The semantics is illustrated by an example of a health monitoring system.