Database technology is currently being pushed by the needs of new applications and pulled by the oppor- tunities of novel developments in hardware and systems architecture. The invited paper, two panel sessions and 27 papers in this volume report on how the technology is currently extending. One broad area covered is extended database semantics, including data models and data types, databases and logic, complex objects, and expert system approaches to databases. The other area covered is raw architectures and increased database systems support, including novel transaction models, data distribution and replication, database administration, and access efficiency.

The Fourth International Workshop on Database Programming Languages - Object Models and Languages (DBPL-4) took place in Manhattan, New York City, 30 August-1 September 1993. The areas of interest and the format of DBPL-4 focused on the integration of programming languages, object models, type systems and database systems. As in the previous DBPL workshops, the setting was informal, allowing the participants to actively discuss and argue about the ideas presented in the talks. The comments and remarks made by the participants during and after the presentations were taken into account in the preparation of the final versions of the papers. The result, we believe, is a set of excellent papers. The DBPL sequence is closely related to the sequence of International Workshops on Persistent Object Systems (POS), first started in 1985. While the DBPL workshops focus on language and model issues, the POS workshops have focused on implementation issues; thus the two sequences complement each other. Many researchers participate in both workshop series. The eight sessions of the technical program of DBPL-4 were as follows: 1. Bulk types and their query languages (two sessions). 2. Object models and languages. 3. Data types with order. 4. Mechanisms to support persistence, reflection, and extensibility. 5. Query optimization and integrity constraints. 6. Logic-based models. 7. Implementation and performance issues.

This volume results from the four-day scientific Second International East/West Database Workshop which took place 25th-28th September 1994, in Klagenfurt, Austria, continuing a series of workshops started in Kiev in 1990 (Lecture Notes in Computer Science No. 504, Springer, "Next Generation Information System Technology"). The aims of this workshop are twofold: first, to provide a forum for the presentation and in-depth discussion of scientific achievements in the field of advanced databases that will effectively improve the building and use of future information systems; second, to establish and increase communication between research communities which were formerly separated and, therefore, had only rare opportunities to interact. It should establish contacts between researchers from the East and from the West to make exchange of ideas possible and to trigger collaborations. However, it is not only political borders which change their perviousness as a result of -or giving rise to -new autonomies or new possibilities for interaction and collaboration. The same happens with the borders between scientific areas, in particular in the dynamically evolving areas of computer science. Databases and programming languages are integrated in object oriented databases, database and information retrieval technology form together the basis for modern (multimedia) information systems. Furthermore, the borders between different information systems change and allow various forms of collaboration while maintaining different degrees of autonomy. Heterogeneous and distributed databases are enabling technologies for these systems.

This volume aims to present recent advances in database technology from the viewpoint of the novel database paradigms proposed in the last decade. It focuses on the theory of the extended relational model and an example of an extended relational database programming language, Algres, is described. A free copy of Algres complements this work, and is available on the Internet. Audience: This work will be of interest to graduate students following advanced database courses, advanced data-oriented applications developers, and researchers in the field of database programming languages and software engineering who need a flexible prototyping platform for the development of software tools.

This book constitutes the thoroughly refereed post-workshop proceedings of the 6th International Workshop on Database Programming Languages, DBPL-6, held in Estes Park, Colorado, USA, in August 1997. The 20 revised full papers presented have gone through two rounds of reviewing and selection. Also included are two invited talks, the transcription of a panel discussion and an introductory survey by the volume editors. The papers address all current aspects of database programming languages, in particular spatial databases, typing, query languages for new applications, views, expressive power, aggregate queries, cooperative work, and transactions.

As the costs of power and timing become increasingly difficult to manage in traditional synchronous systems, designers are being forced to look at asynchronous alternatives. Based on reworked and expanded papers from the VII Banff Higher Order Workshop, this volume examines asynchronous methods which have been used in large circuit design, ranging from initial formal specification to more standard finite state machine based control models. Written by leading practitioners in the area, the papers cover many aspects of current practice including practical design, silicon compilation, and applications of formal specification. It also includes a state-of-the-art survey of asynchronous hardware design. The resulting volume will be invaluable to anyone interested in designing correct asynchronous circuits which exhibit high performance or low power operation.