117,675 research outputs found
Construction and Verification of Performance and Reliability Models
Over the last two decades formal methods have been extended towards performance and reliability evaluation. This paper tries to provide a rather intuitive explanation of the basic concepts and features in this area.
Instead of striving for mathematical rigour, the intention is to give an illustrative introduction to the basics of stochastic models, to stochastic modelling using process algebra, and to model checking as a technique to analyse stochastic models
Specification Patterns for Robotic Missions
Mobile and general-purpose robots increasingly support our everyday life,
requiring dependable robotics control software. Creating such software mainly
amounts to implementing their complex behaviors known as missions. Recognizing
the need, a large number of domain-specific specification languages has been
proposed. These, in addition to traditional logical languages, allow the use of
formally specified missions for synthesis, verification, simulation, or guiding
the implementation. For instance, the logical language LTL is commonly used by
experts to specify missions, as an input for planners, which synthesize the
behavior a robot should have. Unfortunately, domain-specific languages are
usually tied to specific robot models, while logical languages such as LTL are
difficult to use by non-experts. We present a catalog of 22 mission
specification patterns for mobile robots, together with tooling for
instantiating, composing, and compiling the patterns to create mission
specifications. The patterns provide solutions for recurrent specification
problems, each of which detailing the usage intent, known uses, relationships
to other patterns, and---most importantly---a template mission specification in
temporal logic. Our tooling produces specifications expressed in the LTL and
CTL temporal logics to be used by planners, simulators, or model checkers. The
patterns originate from 245 realistic textual mission requirements extracted
from the robotics literature, and they are evaluated upon a total of 441
real-world mission requirements and 1251 mission specifications. Five of these
reflect scenarios we defined with two well-known industrial partners developing
human-size robots. We validated our patterns' correctness with simulators and
two real robots
Policy capturing and two level specifications of policies for human and software processing
In recent few years, the use of "policies" in the management of the behavior of large-scale, dynamic or distributed systems is gaining importance. In the policy research area, how to capture policies is the first problem scientists need to solve. Policies can be specified in three ways: a Policy Definition Language (PDL), a formal logic-based policy representation language or an informal natural language. Generally, an editor and a policy management tool are used to input these specifications. Because both the PDLs and the formal logic-based policy representation languages are very complex and more suitable for machine communication instead of human communication, their usages are limited to a small group of professional people. In this thesis, two levels of policy specifications are introduced. A Restricted Natural Language (RNL), as the high-level policy specification, is used for human-computer interactions. Compared to the PDLs and the formal logic-based policy representation languages, the RNL is both easy to use and easy to learn. It enables a wider group of end users, especially the novice users, to participate in stating the policies. A logic-based formal representation, as the low-level policy specification, is then used for further machine-oriented processing in policy-based systems. A methodology of how to construct such a RNL is also presented and the methodology is applied to two different cases. In the implementation part of the thesis, a RNL user interface (RNLI) named the Virtual Thesis Office (VTO) System is also developed and presente
Using Event Calculus to Formalise Policy Specification and Analysis
As the interest in using policy-based approaches for systems management grows, it is becoming increasingly important to develop methods for performing analysis and refinement of policy specifications. Although this is an area that researchers have devoted some attention to, none of the proposed solutions address the issues of analysing specifications that combine authorisation and management policies; analysing policy specifications that contain constraints on the applicability of the policies; and performing a priori analysis of the specification that will both detect the presence of inconsistencies and explain the situations in which the conflict will occur. We present a method for transforming both policy and system behaviour specifications into a formal notation that is based on event calculus. Additionally it describes how this formalism can be used in conjunction with abductive reasoning techniques to perform a priori analysis of policy specifications for the various conflict types identified in the literature. Finally, it presents some initial thoughts on how this notation and analysis technique could be used to perform policy refinement
Consistency in Multi-Viewpoint Architectural Design of Enterprise Information Systems
Different stakeholders in the design of an enterprise information system have their own view on that design. To help produce a coherent design this paper presents a framework that aids in specifying relations between such views. To help produce a consistent design the framework also aids in specifying consistency rules that apply to the view relations and in checking the consistency according to those rules. The framework focuses on the higher levels of abstraction in a design, we refer to design at those levels of abstraction as architectural design. The highest level of abstraction that we consider is that of business process design and the lowest level is that of software component design. The contribution of our framework is that it provides a collection of basic concepts that is common to viewpoints in the area of enterprise information systems. These basic concepts aid in relating viewpoints by providing: (i) a common terminology that helps stakeholders to understand each others concepts; and (ii) a basis for defining re-usable consistency rules. In particular we define re-usable rules to check consistency between behavioural views that overlap or are a refinement of each other. We also present an architecture for a tool suite that supports our framework. We show that our framework can be applied, by performing a case study in which we specify the relations and consistency rules between the RM-ODP enterprise, computational and information viewpoints
Formal Verification of Safety Properties for Ownership Authentication Transfer Protocol
In ubiquitous computing devices, users tend to store some valuable
information in their device. Even though the device can be borrowed by the
other user temporarily, it is not safe for any user to borrow or lend the
device as it may cause private data of the user to be public. To safeguard the
user data and also to preserve user privacy we propose and model the technique
of ownership authentication transfer. The user who is willing to sell the
device has to transfer the ownership of the device under sale. Once the device
is sold and the ownership has been transferred, the old owner will not be able
to use that device at any cost. Either of the users will not be able to use the
device if the process of ownership has not been carried out properly. This also
takes care of the scenario when the device has been stolen or lost, avoiding
the impersonation attack. The aim of this paper is to model basic process of
proposed ownership authentication transfer protocol and check its safety
properties by representing it using CSP and model checking approach. For model
checking we have used a symbolic model checker tool called NuSMV. The safety
properties of ownership transfer protocol has been modeled in terms of CTL
specification and it is observed that the system satisfies all the protocol
constraint and is safe to be deployed.Comment: 16 pages, 7 figures,Submitted to ADCOM 201
A review of GIS-based information sharing systems
GIS-based information sharing systems have been implemented in many of England and Wales' Crime and Disorder Reduction Partnerships (CDRPs). The information sharing role of these systems is seen as being vital to help in the review of crime, disorder and misuse of drugs; to sustain strategic objectives, to monitor interventions and initiatives; and support action plans for service delivery. This evaluation into these systems aimed to identify the lessons learned from existing systems, identify how these systems can be best used to support the business functions of CDRPs, identify common weaknesses across the systems, and produce guidelines on how these systems should be further developed. At present there are in excess of 20 major systems distributed across England and Wales. This evaluation considered a representative sample of ten systems. To date, little documented evidence has been collected by the systems that demonstrate the direct impact they are having in reducing crime and disorder, and the misuse of drugs. All point to how they are contributing to more effective partnership working, but all systems must be encouraged to record how they are contributing to improving community safety. Demonstrating this impact will help them to assure their future role in their CDRPs. By reviewing the systems wholly, several key ingredients were identified that were evident in contributing to the effectiveness of these systems. These included the need for an effective partnership business model within which the system operates, and the generation of good quality multi-agency intelligence products from the system. In helping to determine the future development of GIS-based information sharing systems, four key community safety partnership business service functions have been identified that these systems can most effectively support. These functions support the performance review requirements of CDRPs, operate a problem solving scanning and analysis role, and offer an interface with the public. By following these business service functions as a template will provide for a more effective application of these systems nationally
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