An Institution for Event-B

This paper presents a formalisation of the Event-B formal specification language in terms of the theory of institutions. The main objective of this paper is to provide: (1) a mathematically sound semantics and (2) modularisation constructs for Event-B using the specification-building operations of the theory of institutions. Many formalisms have been improved in this way and our aim is thus to define an appropriate institution for Event-B, which we call EVT. We provide a definition of EVT and the proof of its satisfaction condition. A motivating example of a traffic-light simulation is presented to illustrate our approach

Event-B in the Institutional Framework: Defining a Semantics, Modularisation Constructs and Interoperability for a Specification Language

Event-B is an industrial-strength specification language for verifying the properties of a given system’s specification. It is supported by its Eclipse-based IDE, Rodin, and uses the process of refinement to model systems at different levels of abstraction. Although a mature formalism, Event-B has a number of limitations. In this thesis, we demonstrate that Event-B lacks formally defined modularisation constructs. Additionally, interoperability between Event-B and other formalisms has been achieved in an ad hoc manner. Moreover, although a formal language, Event-B does not have a formal semantics. We address each of these limitations in this thesis using the theory of institutions. The theory of institutions provides a category-theoretic way of representing a formalism. Formalisms that have been represented as institutions gain access to an array of generic specification-building operators that can be used to modularise specifications in a formalismindependent manner. In the theory of institutions, there are constructs (known as institution (co)morphisms) that provide us with the facility to create interoperability between formalisms in a mathematically sound way. The main contribution of this thesis is the definition of an institution for Event-B, EVT, which allows us to address its identified limitations. To this end, we formally define a translational semantics from Event- B to EVT. We show how specification-building operators can provide a unified set of modularisation constructs for Event-B. In fact, the institutional framework that we have incorporated Event-B into is more accommodating to modularisation than the current state-of-the-art for Rodin. Furthermore, we present institution morphisms that facilitate interoperability between the respective institutions for Event-B and UML. This approach is more generic than the current approach to interoperability for Event-B and in fact, allows access to any formalism or logic that has already been defined as an institution. Finally, by defining EVT, we have outlined the steps required in order to include similar formalisms into the institutional framework. Hence, this thesis acts as a template for defining an institution for a specification language

Building Specifications in the Event-B Institution

This paper describes a formal semantics for the Event-B specification language using the theory of institutions. We define an institution for Event-B, EVT, and prove that it meets the validity requirements for satisfaction preservation and model amalgamation. We also present a series of functions that show how the constructs of the Event-B specification language can be mapped into our institution. Our semantics sheds new light on the structure of the Event-B language, allowing us to clearly delineate three constituent sub-languages: the superstructure, infrastructure and mathematical languages. One of the principal goals of our semantics is to provide access to the generic modularisation constructs available in institutions, including specification-building operators for parameterisation and refinement. We demonstrate how these features subsume and enhance the corresponding features already present in Event-B through a detailed study of their use in a worked example. We have implemented our approach via a parser and translator for Event-B specifications, EBtoEVT, which also provides a gateway to the Hets toolkit for heterogeneous specification.Comment: 54 pages, 25 figure

Building Specifications in the Event-B Institution

This paper describes a formal semantics for the Event-B specification language using the theory of institutions. We define an institution for Event-B, EVT, and prove that it meets the validity requirements for satisfaction preservation and model amalgamation. We also present a series of functions that show how the constructs of the Event-B specification language can be mapped into our institution. Our semantics sheds new light on the structure of the Event-B language, allowing us to clearly delineate three constituent sub-languages: the superstructure, infrastructure and mathematical languages. One of the principal goals of our semantics is to provide access to the generic modularisation constructs available in institutions, including specification-building operators for parameterisation and refinement. We demonstrate how these features subsume and enhance the corresponding features already present in Event-B through a detailed study of their use in a worked example. We have implemented our approach via a parser and translator for Event-B specifications, EBtoEVT, which also provides a gateway to the Hets toolkit for heterogeneous specification

Early precut fistulotomy for biliary access: time to change the paradigm of "the later, the better?"

The precut timing during the biliary cannulation algorithm is a subject of controversy. Some studies suggest that early institution of precut is a safe and effective strategy even though the extent to which this approach may affect the duration of the ERCP is seldom addressed. OBJECTIVE: To assess the success, safety, and procedure duration of an early precut fistulotomy (group A) versus a classic precut strategy after a difficult biliary cannulation (group B). DESIGN: Single-center, prospective cohort study. SETTING: University-affiliated hospital. PATIENTS: A total of 350 patients with a naïve papilla. INTERVENTIONS: Standard biliary cannulation followed by needle-knife fistulotomy (NKF). MAIN OUTCOME MEASUREMENTS: Biliary cannulation rate, NKF success, adverse events, and ERCP duration. RESULTS: The overall cannulation rate was similar, at 96% and 94% for groups A and B, respectively. The adverse event rate was 6.2% and 6.4%, respectively, with pancreatitis as the most frequent adverse event (group A, 3.9%; group B, 5.2%). The mean ERCP duration was, however, significantly shorter in group A, both when biliary cannulation was achieved without precutting (14 minutes vs 25 minutes, P < .001) as well as when biliary cannulation was attempted after NKF (18 minutes vs 31 minutes, P < .0001). LIMITATIONS: Single-center study design, referral center. CONCLUSIONS: If the endoscopist is experienced in ERCP and precut techniques, an early precut strategy should be the preferred cannulation strategy because this approach is as safe and effective as the late fistulotomy approach and substantially reduces ERCP duration

Justice Kagan Highlights South Hall Dedication Weekend

At the dedication of South Hall, the focus was on the buildings importance to a Michigan Law legal education and the institution\u27s gratitude for the wxtraordinarily generous donors who made the building possible. Speakers at the event-officiated by Bruce Bickner, \u2768, chair of the building fundraising committee-included Justice Kagan, U-M President Mary Sue Coleman, U-M Board of Regents Chairman Laurence B. Deitch, \u2772, and Dean Caminker. During dedocatopm weekend, Justice Kagan gave an inside look at the Supreme Court at a Friday morning talk, She said justices are not motivated to rule in certain cases to favor or disfavor a particular president, that members of the the Court genuinely like and respect one another, and that she-the junior justice-has tasks such as serving on the Court\u27s cafeteria committee

An Institutional Framework for Heterogeneous Formal Development in UML

We present a framework for formal software development with UML. In contrast to previous approaches that equip UML with a formal semantics, we follow an institution based heterogeneous approach. This can express suitable formal semantics of the different UML diagram types directly, without the need to map everything to one specific formalism (let it be first-order logic or graph grammars). We show how different aspects of the formal development process can be coherently formalised, ranging from requirements over design and Hoare-style conditions on code to the implementation itself. The framework can be used to verify consistency of different UML diagrams both horizontally (e.g., consistency among various requirements) as well as vertically (e.g., correctness of design or implementation w.r.t. the requirements)

Strategic application of events

This paper explores the area of strategy and events through a qualitative study. Organisations are increasingly seeking to achieve strategic objectives though the delivery of events. Particularly, as regards the role of events in the communication of brand strategy. This paper seeks to illuminate the underpinning reasoning for this trend, and examine prevalent issues relating to event management and event experience. There is a critical evaluation of the factors that facilitate and constrain events in supporting organisational strategy, with a number of themes identified that impede events from realising their strategic potential

Using electronic health records to support clinical trials: a report on stakeholder engagement for EHR4CR

Background. The conduct of clinical trials is increasingly challenging due to greater complexity and governance requirements as well as difficulties with recruitment and retention. Electronic Health Records for Clinical Research (EHR4CR) aims at improving the conduct of trials by using existing routinely collected data, but little is known about stakeholder views on data availability, information governance, and acceptable working practices. Methods. Senior figures in healthcare organisations across Europe were provided with a description of the project and structured interviews were subsequently conducted to elicit their views. Results. 37 structured interviewees in Germany, UK, Switzerland, and France indicated strong support for the proposed EHR4CR platform. All interviewees reported that using the platform for assessing feasibility would enhance the conduct of clinical trials and the majority also felt it would reduce workloads. Interviewees felt the platform could enhance trial recruitment and adverse event reporting but also felt it could raise either ethical or information governance concerns in their country. Conclusions. There was clear support for EHR4CR and a belief that it could reduce workloads and improve the conduct and quality of trials. However data security, privacy, and information governance issues would need to be carefully managed in the development of the platform