Analysis of Petri Nets and Transition Systems

This paper describes a stand-alone, no-frills tool supporting the analysis of (labelled) place/transition Petri nets and the synthesis of labelled transition systems into Petri nets. It is implemented as a collection of independent, dedicated algorithms which have been designed to operate modularly, portably, extensibly, and efficiently.Comment: In Proceedings ICE 2015, arXiv:1508.0459

On the Decidability of Non Interference over Unbounded Petri Nets

Non-interference, in transitive or intransitive form, is defined here over unbounded (Place/Transition) Petri nets. The definitions are adaptations of similar, well-accepted definitions introduced earlier in the framework of labelled transition systems. The interpretation of intransitive non-interference which we propose for Petri nets is as follows. A Petri net represents the composition of a controlled and a controller systems, possibly sharing places and transitions. Low transitions represent local actions of the controlled system, high transitions represent local decisions of the controller, and downgrading transitions represent synchronized actions of both components. Intransitive non-interference means the impossibility for the controlled system to follow any local strategy that would force or dodge synchronized actions depending upon the decisions taken by the controller after the last synchronized action. The fact that both language equivalence and bisimulation equivalence are undecidable for unbounded labelled Petri nets might be seen as an indication that non-interference properties based on these equivalences cannot be decided. We prove the opposite, providing results of decidability of non-interference over a representative class of infinite state systems.Comment: In Proceedings SecCo 2010, arXiv:1102.516

Synthesis of Bounded Choice-Free Petri Nets

This paper describes a synthesis algorithm tailored to the construction of choice-free Petri nets from finite persistent transition systems. With this goal in mind, a minimised set of simplified systems of linear inequalities is distilled from a general region-theoretic approach, leading to algorithmic improvements as well as to a partial characterisation of the class of persistent transition systems that have a choice-free Petri net realisation

Traps characterize home states in free choice systems

AbstractFree choice nets are a subclass of Petri nets allowing to model concurrency and nondeterministic choice, but with the restriction that choices cannot be influenced externally. Home states are ground markings which can be reached from any other reachable marking of a system. A trap is a structurally defined part of a net with the property that once it is marked (that is, carries at least one token), it will remain remarked in any successor marking.The main result of this paper characterizes the home states of a live and bounded free choice system by the property that all traps are marked. This characterization leads to a polynomial-time algorithm for deciding the home state property. Other consequences include the proof that executing all parts of a net at least once necessarily leads to a home state; this has been a long standing conjecture

Das Ländliche als kulturelle Kategorie: aktuelle kulturwissenschaftliche Perspektiven auf Stadt-Land-Beziehungen

Das Ländliche hat Konjunktur. Zwischen medialer »Landlust« und realem Strukturwandel in den ländlichen Räumen Europas differenziert es sich dynamisch aus. Idylle oder Problemregion? Arbeitsort oder Freizeitpark? Repräsentationen und lebensweltliche Erfahrungen des Ländlichen avancieren zu einem alltagskulturellen Konfliktfeld, auf dem sich vor einem historischen Hintergrund elementare Problemlagen der Gegenwart und die Komplexität von kulturellen Land-Stadt-Beziehungen spiegeln.Die Beiträge des Bandes liefern hierzu Einsichten aus der Forschungsperspektive der Europäischen Ethnologie und rahmen das Thema damit für historische und gegenwartsbezogene Kulturanalysen begrifflich, methodisch und theoretisch