Distance Between Mutually Reachable Petri Net Configurations

Petri nets are a classical model of concurrency widely used and studied in formal verification with many applications in modeling and analyzing hardware and software, data bases, and reactive systems. The reachability problem is central since many other problems reduce to reachability questions. In 2011, we proved that a variant of the reachability problem, called the reversible reachability problem is exponential-space complete. Recently, this problem found several unexpected applications in particular in the theory of population protocols. In this paper we revisit the reversible reachability problem in order to prove that the minimal distance in the reachability graph of two mutually reachable configurations is linear with respect to the Euclidean distance between those two configurations

A Petri Net Variability Model for Software Product Lines

Variability is defined as the possibility that a system has to be extended, changed, localized or configured in order to be used in a particular context. Variability specification in a software product line (SPL) is a main activity where product families are specified in terms of variants and dependencies. One way of defining the variability of a SPL is through a feature model (FM). However the product families obtained can present feasibility problems, for instance, inclusion rules that can result contradictory which is translated in a set of features impossible to be incorporated into any product. Such inconveniences may come from the initial feature model developed as well from modifications introduced to satisfy new demands. In this paper a tool based on Petri nets is proposed in order to represent and analyse FMs as well as detecting the problems mentioned before.Fil: Díaz Ferreyra, Nicolás Emilio. Universidad Tecnológica Nacional. Facultad Regional Santa Fe; ArgentinaFil: Martinez, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); ArgentinaFil: Leone, Horacio Pascual. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); ArgentinaFil: Gonnet, Silvio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); Argentin

A Petri Net approach for representing Orthogonal Variability Models

The software product line (SPL) paradigm is used for developing software system products from a set of reusable artifacts, known as platform. The Orthogonal Variability Modeling (OVM) is a technique for representing and managing the variability and composition of those artifacts for deriving products in the SPL. Nevertheless, OVM does not support the formal analysis of the models. For example, the detection of dead artifacts (i.e., artifcats that cannot be included in any product) is an exhaustive activity which implies the verification of relationships between artifacs, artifacts parents, and so on. In this work, we introduce a Petri nets approach for representing and analyzing OVM models. The proposed net is built from elemental topologies that represents OVM concepts and relationships. Finally, we simulate the net and study their properties in order to avoid the product feasibility problems.Fil: Martinez, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); ArgentinaFil: Leone, Horacio Pascual. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); ArgentinaFil: Gonnet, Silvio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo y Diseño (i); Argentin

Task planning with uncertainty for robotic systems

In a practical robotic system, it is important to represent and plan sequences of operations and to be able to choose an efficient sequence from them for a specific task. During the generation and execution of task plans, different kinds of uncertainty may occur and erroneous states need to be handled to ensure the efficiency and reliability of the system. An approach to task representation, planning, and error recovery for robotic systems is demonstrated. Our approach to task planning is based on an AND/OR net representation, which is then mapped to a Petri net representation of all feasible geometric states and associated feasibility criteria for net transitions. Task decomposition of robotic assembly plans based on this representation is performed on the Petri net for robotic assembly tasks, and the inheritance of properties of liveness, safeness, and reversibility at all levels of decomposition are explored. This approach provides a framework for robust execution of tasks through the properties of traceability and viability. Uncertainty in robotic systems are modeled by local fuzzy variables, fuzzy marking variables, and global fuzzy variables which are incorporated in fuzzy Petri nets. Analysis of properties and reasoning about uncertainty are investigated using fuzzy reasoning structures built into the net. Two applications of fuzzy Petri nets, robot task sequence planning and sensor-based error recovery, are explored. In the first application, the search space for feasible and complete task sequences with correct precedence relationships is reduced via the use of global fuzzy variables in reasoning about subgoals. In the second application, sensory verification operations are modeled by mutually exclusive transitions to reason about local and global fuzzy variables on-line and automatically select a retry or an alternative error recovery sequence when errors occur. Task sequencing and task execution with error recovery capability for one and multiple soft components in robotic systems are investigated

Events in computation

SIGLEAvailable from British Library Document Supply Centre- DSC:D36018/81 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

A Petri Net Variability Model for Software Product Lines

Variability is defined as the possibility that a system has to be extended, changed, localized or configured in order to be used in a particular context. Variability specification in a software product line (SPL) is a main activity where product families are specified in terms of variants and dependencies. One way of defining the variability of a SPL is through a feature model (FM). However, the product families obtained can present feasibility problems, for instance, inclusion rules that can result contradictory which is translated in a set of features impossible to be incorporated into any product. Such inconveniences may come from the initial feature model developed as well from modifications introduced to satisfy new demands. In this paper a tool based on Petri nets is proposed in order to represent and analyze FMs as well as detecting the problems mentioned before.Sociedad Argentina de Informática e Investigación Operativ

Dynamic Cutoff Detection in Parameterized Concurrent Programs

Abstract. We consider the class of finite-state programs executed by an unbounded number of replicated threads communicating via shared variables. The thread-state reachability problem for this class is essential in software verification using predicate abstraction. While this problem is decidable via Petri net coverability analysis, techniques solely based on coverability suffer from the problem’s exponential-space complexity. In this paper, we present an alternative method based on a thread-state cutoff: a number n of threads that suffice to generate all reachable thread states. We give a condition, verifiable dynamically during reachability analysis for increasing n, that is sufficient to conclude that n is a cutoff. We then make the method complete, via a coverability query that is of low cost in practice. We demonstrate the efficiency of the approach on Petri net encodings of communication protocols, as well as on non-recursive Boolean programs run by arbitrarily many parallel threads.