473 research outputs found
A Linear-Time Branching-Time Spectrum for Behavioral Specification Theories
We propose behavioral specification theories for most equivalences in the
linear-time--branching-time spectrum. Almost all previous work on specification
theories focuses on bisimilarity, but there is a clear interest in
specification theories for other preorders and equivalences. We show that
specification theories for preorders cannot exist and develop a general scheme
which allows us to define behavioral specification theories, based on
disjunctive modal transition systems, for most equivalences in the
linear-time--branching-time spectrum
Bisimulation of Labelled State-to-Function Transition Systems Coalgebraically
Labeled state-to-function transition systems, FuTS for short, are
characterized by transitions which relate states to functions of states over
general semirings, equipped with a rich set of higher-order operators. As such,
FuTS constitute a convenient modeling instrument to deal with process languages
and their quantitative extensions in particular. In this paper, the notion of
bisimulation induced by a FuTS is addressed from a coalgebraic point of view. A
correspondence result is established stating that FuTS-bisimilarity coincides
with behavioural equivalence of the associated functor. As generic examples,
the equivalences underlying substantial fragments of major examples of
quantitative process algebras are related to the bisimilarity of specific FuTS.
The examples range from a stochastic process language, PEPA, to a language for
Interactive Markov Chains, IML, a (discrete) timed process language, TPC, and a
language for Markov Automata, MAL. The equivalences underlying these languages
are related to the bisimilarity of their specific FuTS. By the correspondence
result coalgebraic justification of the equivalences of these calculi is
obtained. The specific selection of languages, besides covering a large variety
of process interaction models and modelling choices involving quantities,
allows us to show different classes of FuTS, namely so-called simple FuTS,
combined FuTS, nested FuTS, and general FuTS
Characterising Probabilistic Processes Logically
In this paper we work on (bi)simulation semantics of processes that exhibit
both nondeterministic and probabilistic behaviour. We propose a probabilistic
extension of the modal mu-calculus and show how to derive characteristic
formulae for various simulation-like preorders over finite-state processes
without divergence. In addition, we show that even without the fixpoint
operators this probabilistic mu-calculus can be used to characterise these
behavioural relations in the sense that two states are equivalent if and only
if they satisfy the same set of formulae.Comment: 18 page
Automatic Synthesis of Real Time Systems
This paper presents a method for automatically constructing real time systems directly from their specifications. The model-construction problem is considered for implicit specifications of the form: (A_1 | . . . | A_n | X) sat S where S is a real time (logical) specification, A_1, ... , A_n are given (regular) timed agents and the problem is to decide whether there exists (and if possible exhibit) a real time agent X which when put in parallel with A_1, ..., A_n will yield a network satisfying S. The method presented proceeds in two steps: first, the implicit specification of X is transformed into an equivalent direct specification of X; second, a model for this direct specification is constructed (if possible) using a direct model construction algorithm. A prototype implementation of our method has been added to the real time verification tool EPSILON
Knowledge-based support in Non-Destructive Testing for health monitoring of aircraft structures
Maintenance manuals include general methods and procedures for industrial maintenance and they contain information about principles of maintenance methods. Particularly, Non-Destructive Testing (NDT) methods are important for the detection of aeronautical defects and they can be used for various kinds of material and in different environments. Conventional non-destructive evaluation inspections are done at periodic maintenance checks. Usually, the list of tools used in a maintenance program is simply located in the introduction of manuals, without any precision as regards to their characteristics, except for a short description of the manufacturer and tasks in which they are employed. Improving the identification concepts of the maintenance tools is needed to manage the set of equipments and establish a system of equivalence: it is necessary to have a consistent maintenance conceptualization, flexible enough to fit all current equipment, but also all those likely to be added/used in the future. Our contribution is related to the formal specification of the system of functional equivalences that can facilitate the maintenance activities with means to determine whether a tool can be substituted for another by observing their key parameters in the identified characteristics. Reasoning mechanisms of conceptual graphs constitute the baseline elements to measure the fit or unfit between an equipment model and a maintenance activity model. Graph operations are used for processing answers to a query and this graph-based approach to the search method is in-line with the logical view of information retrieval. The methodology described supports knowledge formalization and capitalization of experienced NDT practitioners. As a result, it enables the selection of a NDT technique and outlines its capabilities with acceptable alternatives
Automated Synthesis of Enforcing Mechanisms for Security Properties in a Timed Setting
AbstractIn [Martinelli, F. and I. Matteucci, Modeling security automata with process algebras and related results (2006), presented at the 6th International Workshop on Issues in the Theory of Security (WITS '06) - Informal proceedings; Martinelli, F. and I. Matteucci, Through modeling to synthesis of security automata (2006), accepted to STM06. To appeare in ENTCS] we have presented an approach for enforcing security properties. It is based on the automatic synthesis of controller programs that are able to detect and eventually prevent possible wrong action performed by an external agent. Here, we extend this approach also to a timed setting. Under certain assumptions, we are also able to enforce several information flow properties. We show how to deal with parameterized systems
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