Extended ML: Past, present and future

An overview of past, present and future work on the Extended ML formal program development framework is given, with emphasis on two topics of current active research: the semantics of the Extended ML specification language, and tools to support formal program development

The Information Content of Earnings Announcements in Regulated and Deregulated Markets: The Case of the Airline Industry

Most of the accounting research examining the information content of earnings assumes a competitive market framework. Little research has been devoted to the value relevance of earnings announcements in regulated markets. This paper examines the information content of earnings releases under two economic conditions facing the airline industry: regulation and deregulation (i.e., competition). We hypothesize that in a deregulated (competitive) environment, there is greater competition, causing more risk and uncertainty for the investor in setting security prices. Therefore, earnings\u27 releases provide more useful information in resolving uncertainties and in formulating and revising the investor\u27s beliefs regarding future earnings and prices in deregulated than for regulated markets. Three critical event periods are examined: the regulation period (1973 - 1975), the transition period (1976 - 1978), and the deregulation period (1979 - 1981). A revaluation index (RI) and a standardized revaluation index (SRI) are used to examine the extent of airline stock price revaluation in response to quarterly accounting earnings releases during the three critical event periods. The results indicate that earnings announcements have value relevance in setting security prices in both regulated and deregulated market conditions. However, the level of the market revaluation to earnings releases is dependent on market structure. The market revaluation to earnings releases is greater in a deregulated (competitive) period than in a regulated one. This result confirms the hypothesis that earnings have more value relevance in competitive markets than in regulated ones. The findings of this research have direct implications for the level of accounting disclosure and the extent of financial reporting in a given market structure. Since financial reporting is a costly process, it becomes important to identify the circumstances under which the level of financial disclosure should be expanded or reduce

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)

A coalgebraic perspective on logical interpretations

In Computer Science stepwise refinement of algebraic specifications is a well-known formal methodology for rigorous program development. This paper illustrates how techniques from Algebraic Logic, in particular that of interpretation, understood as a multifunction that preserves and reflects logical consequence, capture a number of relevant transformations in the context of software design, reuse, and adaptation, difficult to deal with in classical approaches. Examples include data encapsulation and the decomposition of operations into atomic transactions. But if interpretations open such a new research avenue in program refinement, (conceptual) tools are needed to reason about them. In this line, the paper’s main contribution is a study of the correspondence between logical interpretations and morphisms of a particular kind of coalgebras. This opens way to the use of coalgebraic constructions, such as simulation and bisimulation, in the study of interpretations between (abstract) logics.Fundação para a Ciência e a Tecnologia (FCT