3,389 research outputs found
Verifying temporal properties of systems with applications to petri nets
This thesis provides a powerful general-purpose proof technique for the verification
of systems, whether finite or infinite. It extends the idea of finite local
model-checking, which was introduced by Stirling and Walker: rather than
traversing the entire state space of a model, as is done for model-checking in
the sense of Emerson, Clarke et al. (checking whether a (finite) model satisfies
a formula), local model-checking asks whether a particular state satisfies a formula,
and only explores the nearby states far enough to answer that question.
The technique used was a tableau method, constructing a tableau according to
the formula and the local structure of the model. This tableau technique is here
generalized to the infinite case by considering sets of states, rather than single
states; because the logic used, the propositional modal mu-calculus, separates
simple modal and boolean connectives from powerful fix-point operators (which
make the logic more expressive than many other temporal logics), it is possible
to give a relatively straightforward set of rules for constructing a tableau. Much
of the subtlety is removed from the tableau itself, and put into a relation on the
state space defined by the tableau-the success of the tableau then depends on
the well-foundedness of this relation.
This development occupies the second and third chapters: the second considers
the modal mu-calculus, and explains its power, while the third develops
the tableau technique itself
The generalized tableau technique is exhibited on Petri nets, and various
standard notions from net theory are shown to play a part in the use of the
technique on nets-in particular, the invariant calculus has a major role.
The requirement for a finite presentation of tableaux for infinite systems
raises the question of the expressive power of the mu-calculus. This is studied in
some detail, and it is shown that on reasonably powerful models of computation,
such as Petri nets, the mu-calculus can express properties that are not merely
undecidable, but not even arithmetical.
The concluding chapter discusses some of the many questions still to be
answered, such as the incorporation of formal reasoning within the tableau
system, and the power required of such reasoning
On Modelling and Analysis of Dynamic Reconfiguration of Dependable Real-Time Systems
This paper motivates the need for a formalism for the modelling and analysis
of dynamic reconfiguration of dependable real-time systems. We present
requirements that the formalism must meet, and use these to evaluate well
established formalisms and two process algebras that we have been developing,
namely, Webpi and CCSdp. A simple case study is developed to illustrate the
modelling power of these two formalisms. The paper shows how Webpi and CCSdp
represent a significant step forward in modelling adaptive and dependable
real-time systems.Comment: Presented and published at DEPEND 201
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Computer-aided analysis of concurrent systems
The introduction of concurrency into programs has added to the complexity of the software design process. This is most evident in the design of communications protocols where concurrency is inherent to the behavior of the system. The complexity exhibited by such software systems makes more evident the needs for computer-aided tools for automatically analyzing behavior.The Distributed Systems project at UCI has been developing a suite of tools, based on Petri nets, which support the design and evaluation of concurrent software systems. This paper focuses attention on one of the tools: the reachability graph analyzer (RGA). This tool provides mechanisms for proving general system properties (e.g., deadlock-freeness) as well as system-specific properties. The tool is sufficiently general to allow a user to apply complex user-defined analysis algorithms to reachability graphs. The alternating-bit protocol with a bounded channel is used to demonstrate the power of the tool and to point to future extensions
Dependability Analysis of Control Systems using SystemC and Statistical Model Checking
Stochastic Petri nets are commonly used for modeling distributed systems in
order to study their performance and dependability. This paper proposes a
realization of stochastic Petri nets in SystemC for modeling large embedded
control systems. Then statistical model checking is used to analyze the
dependability of the constructed model. Our verification framework allows users
to express a wide range of useful properties to be verified which is
illustrated through a case study
A System for Deduction-based Formal Verification of Workflow-oriented Software Models
The work concerns formal verification of workflow-oriented software models
using deductive approach. The formal correctness of a model's behaviour is
considered. Manually building logical specifications, which are considered as a
set of temporal logic formulas, seems to be the significant obstacle for an
inexperienced user when applying the deductive approach. A system, and its
architecture, for the deduction-based verification of workflow-oriented models
is proposed. The process of inference is based on the semantic tableaux method
which has some advantages when compared to traditional deduction strategies.
The algorithm for an automatic generation of logical specifications is
proposed. The generation procedure is based on the predefined workflow patterns
for BPMN, which is a standard and dominant notation for the modeling of
business processes. The main idea for the approach is to consider patterns,
defined in terms of temporal logic,as a kind of (logical) primitives which
enable the transformation of models to temporal logic formulas constituting a
logical specification. Automation of the generation process is crucial for
bridging the gap between intuitiveness of the deductive reasoning and the
difficulty of its practical application in the case when logical specifications
are built manually. This approach has gone some way towards supporting,
hopefully enhancing our understanding of, the deduction-based formal
verification of workflow-oriented models.Comment: International Journal of Applied Mathematics and Computer Scienc
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