Analysing Mutual Exclusion using Process Algebra with Signals

In contrast to common belief, the Calculus of Communicating Systems (CCS) and similar process algebras lack the expressive power to accurately capture mutual exclusion protocols without enriching the language with fairness assumptions. Adding a fairness assumption to implement a mutual exclusion protocol seems counter-intuitive. We employ a signalling operator, which can be combined with CCS, or other process calculi, and show that this minimal extension is expressive enough to model mutual exclusion: we confirm the correctness of Peterson's mutual exclusion algorithm for two processes, as well as Lamport's bakery algorithm, under reasonable assumptions on the underlying memory model. The correctness of Peterson's algorithm for more than two processes requires stronger, less realistic assumptions on the underlying memory model.Comment: In Proceedings EXPRESS/SOS 2017, arXiv:1709.0004

A petri net formalization of a publish-subscribe process system.

Publish/subscribe systems are getting more and more integrated into the execution of business processes in process aware information systems. This integration enables the distribution of the process logic and increases the scalability and adaptability of the process enactment infrastructure. A consequence is however that the original specified process model doesn't accurately represent the actual running process anymore, as the publish/subscribe specific operations are not incorporated into the original model. In this paper we propose a formal model of a publish/subscribe system that can be integrated into a business process model, creating in this way an accurate representation of the actual runtime process. The resulting model can be used for model checking the executable process: inspect system properties, discover problems and validate changes.

A Petri net design, simulation, and verification tool

Increasing desire for thorough simulation and analysis of engineered products is quickly replacing the prototype and test design model. Petri nets are important instruments for modeling concurrent, distributed, asynchronous, parallel, deterministic, and non-deterministic systems. This tool provides designers with the ability to easily specify a Petri net design with an easy to use user interface, then simulate and analyze the Petri net to determine essential design properties using the reachability tree technique. The tool will construct a reachability tree, then analyze the tree for properties of safeness, boundedness, liveness, and conservativeness

Petri nets: 2. Applications

Petri nets offer a versatile modeling framework for complex, distributed, concurrent systems and have been used in a wide range of modeling applications. In Part 1 of this two-part article, we have seen important features and representational power of the Petri net model. We have also seen how the application of firing rules enables Petri nets to capture the dynamics or behavior of the modeled system. In this part, we will first understand how important system properties are modeled by Petri nets and then look into the applications of Petri net models

A Synthesis Method for Designing Shared-Resource Systems

In system synthesis, one needs to derive from a given set of processes a system design which reflects exactly the functionalities of the processes and is free from erroneous situations such as deadlock and capacity overflow. This is especially important for shared-resource systems, in which errors are easily induced because of the sharing of common resources among different competing processes. In this paper, a synthesis method is proposed for designing shared-resource systems. It begins with specifying the given processes as augmented marked graphs. These augmented marked graphs are then synthesized through the fusion of commonplaces which represents the shared resources. The net so obtained serves to represent the integrated system which reflects exactly the functionalities of the processes in the sense that the event sequences as well as the pre-conditions and post-conditions of each event occurrence are preserved. Based on the known properties of augmented marked graphs, the system properties such as liveness, boundedness and reversibility can be analysed effectively. The method is applied to manufacturing system design. Promising results are obtained