4,537 research outputs found
Generalised verification of the observer property in discrete event systems
The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system
Generalised verification of the observer property in discrete event systems
The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system
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
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