The main ideas underlying work on the model-theoretic foundations of algebraic specification and formal program development are presented in an informal way. An attempt is made to offer an overall view, rather than new results, and to focus on the basic motivation behind the technicalities presented elsewhere.

The Prosper (Proof and Specification Assisted Design Environments) project advocates the use of toolkits which allow existing verification tools to be adapted to a more flexible format so that they may be treated as components. A system incorporating such tools becomes another component that can be embedded in an application. This paper describes the Prosper Toolkit which enables this. The nature of communication between components is specified in a language-independent way. It is implemented in several common programming languages to allow a wide variety of tools to have access to the toolkit.

We seek to take some initial steps towards a theory of information that is adequate for understanding and designing systems that process information, i.e., information systems in a broad sense. Formal representations of information are needed in designing, using and maintaining such systems, especially when they are computer based. However, it is also necessary to take account of social context, including how information is produced and used, not merely how it is represented; that is, we need a social theory of information. Ideas from ethnomethodology and semiotics, as well as logic and the sociology of science, are used to explore the nature of information.

Abstract: This paper is an overview of a new approach to requirements � the exposition takes formality and informality as its theme. The approach considers that requirements are information and that information is social. Ethnomethodology and semiotics are used to explore the nature of information and requirements. Some limits of formalization, and the importance of tacit knowledge and evolution motivate new methods for acquiring and tracing requirements. 1

This paper discusses an approach to software architecture based on concepts from parameterized programming, particularly its language of "module expressions." A module expression describes the architecture of a system as an interconnection of component modules, and executing the expression actually builds the system. Language features include: modules parameterized by theories, which declare interfaces; a number of module composition operations; views for binding modules to interfaces; and both vertical and horizontal composition. Modules may involve information hiding, theories may declare semantic restrictions with axioms, and views assert behavioral satisfaction of axioms by a module. Some "laws of software composition" are given, showing how various module composition operations are related. We also show how a variety of architectural styles can be supported, and how this approach can be extended to support evolution and traceability. All this is intended to ease the development of large systems, and in particular, to make reuse more effective in practice.

Introduction Information is the life-blood of modern society. It is largely controlled, distributed and manipulated through software systems that drive communications networks, mediate financial transactions and operate databases of almost anything from recipes, through vehicle registrations and corporate finances, to criminal records. These systems range in scope from personal organizers to networks that girdle the earth. They control access to buildings, allow researchers to communicate results and share ideas, format documents such as financial reports and this book; they monitor and control particle accelerators, production lines, nuclear reactors, satellite trajectories and ballistic missiles, as well as cash dispensers and the family car brakes. Participating in society without encountering such systems is as difficult as cutting a pound of flesh from a man's breast without shedding a jot of blood. Information can be effectively recorded, controlled and used only insofar

Abstract. The software application domain of customer-oriented telephony is worth the attention of specialists in formal methods. Primarily this paper is a tutorial about customer-oriented telephony. It also includes observations about how this domain should be formalized, including critiques of some popular approaches. 1.

ion level of specifications Once we have given the formal models, we can qualify the abstraction degree of the specification language in the sense how much abstract its specifications can be, and so providing some information about at which points in the development process it may be used. The abstraction degree is related to the cardinality of the classes of formal models that are semantics of the specifications. The less abstract specification methods are those where [[SP]] has cardinality 1 or is just an isomorphism class. 2.6.2 Specification semantics The technique used for providing the semantics of specification language is not neutral; indeed such semantics can be given in -- A rather direct, explicit and denotational way (e.g., as done by Hoare for CSP, [19]), by exhibiting the relative class of formal models -- An indirect or implicit way, say as (1) the limit of a diagram in a category, (2) defining that two specifications are semantically equivalent iff their equality ...

Based on the notion of event-based behavioral abstraction (EBBA) we specify properties of object-oriented distributed systems in linear time temporal logic. These properties are then observed at system run-time and it is checked whether or not the system violates the specified behavioral constraints. In our approach, several steps in the testing process can be automized: instrumenting the source code, constructing test-oracles and generating an observer. Taking an industrial example as basis, we discuss how our proposal can be integrated into the software design- and testing process. Keywords Event-based behavioral abstraction, Linear-time Temporal Logic, testing 1 INTRODUCTION We describe a way to automatically generate an implementation that observes the dynamic behavior of an object-oriented distributed system, maintaining a notion of whether or not that behavior violates some predefined properties. Therefore, we are concentrating on the twofold problem of specification and testin...

The challenge of this joint project was to design and implement an environment for the creation of advanced telephone services (Intelligent Network Services) on the basis of a library of basic service components going beyond standard 'clipboard-architectures' with some testing support. The novelty of our approach consists of introducing a declarative specification layer, which is used for the construction of the desired services according to global constraints guaranteeing executability and other consistency conditions. These constraints are the basis for an on-line verification via model checking during the interactive service design process. Important for the success of the method is the high performance and the availability of diagnostic information in the case of failure: Several hundred constraints must be checked in real-time, and the diagnostic information must reflect the responsible constraint violation as concisely as possible, while preserving as much of the structure of the developed service as possible. The corresponding product was presented by Siemens Nixdorf at the Telecom'95 in Geneva and will reach the market this year.