Incremental Construction of Large Specifications: Case Study and Techniques

The RODIN project is an EU-funded project concerned with the provision of methods and tools for rigorous development of complex software-based systems. Ultimately, through the development of open-source tools and techniques, the project aims to make formal methods more appealing and accessible to industry. The project is driven by a number of case studies, each of which is designed to exercise the technology being developed and create methodologies for the future. In this paper we focus on the methodologies being developed in one of the case studies (the CDIS subset). This case study is based on a commercial air traffic information system that was developed using formal methods 14 years ago, and it is still in operation today. The key goals of our approach are to improve the comprehensibility of large specifications and to achieve a complete mechanical proof of consistency

Redevelopment of an industrial case study using Event-B and Rodin

CDIS is a commercial air traffic information system that was developed using formal methods 15 years ago by Praxis, and it is still in operation today. This system is an example of an industrial scale system that has been developed using formal methods. In particular, the functional requirements of the system were specified using VVSL -- a variant of VDM. A subset of the original specification has been chosen to be reconstructed on the Rodin platform based on the new Event-B formalism. The goal of our reconstruction was to overcome three key difficulties of the original formalisation, namely the difficulty of comprehending the original specification, the lack of any mechanical proof of the consistency of the specification and the difficulty of dealing with distribution and atomicity refinement. In this paper we elucidate how a new formal notation and tool can help to overcome these difficulties

Modelling and Refinement in CODA

This paper provides an overview of the CODA framework for modelling and refinement of component-based embedded systems. CODA is an extension of Event-B and UML-B and is supported by a plug-in for the Rodin toolset. CODA augments Event-B with constructs for component-based modelling including components, communications ports, port connectors, timed communications and timing triggers. Component behaviour is specified through a combination of UML-B state machines and Event-B. CODA communications and timing are given an Event-B semantics through translation rules. Refinement is based on Event-B refinement and allows layered construction of CODA models in a consistent way.Comment: In Proceedings Refine 2013, arXiv:1305.563

Delegation to Independent Regulators and the Ratchet Effect

Dynamic principal-agent settings with asymmetric information but no commitment are well known to create a ratchet effect. Here, the most efficient agents must be provided with extra 'information rent' as an incentive to relinquish their informational advantage over an uninformed principal; this causes welfare to fall. We study this problem in the case of regulatory procurement and show that delegation by the government to an independent regulator whose preferences differ from the government's can overcome this inefficiency, and we provide 'conservative' conditions under which this happens. Our solution reflects several aspects of many modern regulatory settings: government commitment to a particular regulator, the provision of independence to that regulator, and heterogeneity across available regulators. Our results also provide an analogy with the literatures on the benefits of delegation to independent principals in other settings, such as monetary policy, financial regulation and trade and hence contribute to this broader research agenda.delegation; ratchet effect; procurement

Contracting, Incentives for Breach, and the Impact of Competition

In this paper we provide an economic perspective on the application of competition law to contracts

Accident Compensation: The Role of Incentive Consumer Choice and Competition

With the exception of the introduction of experience-rated premiums the incorporation of the term "insurance" in the title of the 1992 legislation and the short-lived reforms to the structure of workplace accident compensation in 1998 New Zealand's accident compensation scheme has continued to adhere to the principles laid down in the Woodhouse Report. In particular public monopoly provision comprehensive coverage and mandatory purchase separation from other segments of the market for personal risk (where private insurance companies operate) and cross-subsidies between different categories of insured risk were explicit components of Woodhouse's conception of the scheme. Retention of these aspects of the scheme has been justified by the claim that accident compensation is a component of the social welfare net rather than an insurance scheme and that the social welfare approach is superior from the point of view of those covered by the scheme.This paper reviews three of the economic issues raised by the structure of our accident compensation scheme: the role of incentives the relationship with the broader insurance market and the costs of government monopoly provision. We use our analysis of these issues to consider the veracity of the claim that potential accident victims in New Zealand benefit from our adherence to the principles laid out by the Woodhouse Report. We conclude that the current structure of our scheme creates perverse incentives that substantially reduce its efficiency while also denying those covered by the scheme the potential benefits that would come from consumer choice among competing providers offering a broader range of risk products

Common Elements in the Governance of Deregulated Electricity Markets, Telecommunications Market and Payment Systems

We use the telecommunications industry and electricity market in New Zealand and payments systems in Canada and New Zealand to examine the implications of modern network technology for the organisation and governance of deregulated markets. Our analysis identifies natural monopoly components of networks as the key issue for the governance of these markets. We show how technological change has enhanced the scope for competition and reduced the desirability of public management and regulation in network industries. We argue that where natural monopoly or other problems persist private joint ventures are superior to public sector monopoly as a means of organising the activity. Light-handed regulation in which markets are constrained only by economy-wide competition law provides for the development of efficient private solutions to the special governance problems of network industries

Can an Evaluation of Students’ Stress Levels Help us Manage Anxiety During OSCEs and Other Assessment Modalities?

With an increased awareness of mental health issues, in both the student population and the veterinary profession in general, it is important that we obtain a greater understating of the stress experienced by students so as to better prepare them to deal with stress and ameliorate any negative effects it may have on performance. This study aims to characterise various measurements of stress (e.g. HRV, EEG, cortisol, self-report questionnaire) in students within the School of Veterinary Medicine in familiar test modalities, focussing on OSCE assessment. We would also investigate how performance is impacted and what potential factors may influence stress levels. Ultimately, our aim would be to evaluate intervention strategies to assess if students stress levels and performance can be improved

IL-17 can be protective or deleterious in murine pneumococcal pneumonia

Streptococcus pneumoniae is the major bacterial cause of community-acquired pneumonia, and the leading agent of childhood pneumonia deaths worldwide. Nasal colonization is an essential step prior to infection. The cytokine IL-17 protects against such colonization and vaccines that enhance IL-17 responses to pneumococcal colonization are being developed. The role of IL-17 in host defence against pneumonia is not known. To address this issue, we have utilized a murine model of pneumococcal pneumonia in which the gene for the IL-17 cytokine family receptor, Il17ra, has been inactivated. Using this model, we show that IL-17 produced predominantly from γδ T cells protects mice against death from the invasive TIGR4 strain (serotype 4) which expresses a relatively thin capsule. However, in pneumonia produced by two heavily encapsulated strains with low invasive potential (serotypes 3 and 6B), IL-17 significantly enhanced mortality. Neutrophil uptake and killing of the serotype 3 strain was significantly impaired compared to the serotype 4 strain and depletion of neutrophils with antibody enhanced survival of mice infected with the highly encapsulated SRL1 strain. These data strongly suggest that IL-17 mediated neutrophil recruitment to the lungs clears infection from the invasive TIGR4 strain but that lung neutrophils exacerbate disease caused by the highly encapsulated pneumococcal strains. Thus, whilst augmenting IL-17 immune responses against pneumococci may decrease nasal colonization, this may worsen outcome during pneumonia caused by some strains