The papers in this volume were presented at the 1st Scandinavian Workshop on Algorithm Theory held July 5-8, 1988 in Halmstad, Sweden. The contributions present original research in areas related to algorithm theory, including data structures, computational geometry, and computational complexity. In addition to the selected papers the proceedings include invited papers from I. Munro, K. Mehlhorn, M. Overmars, and D. Wood.

This volume contains the papers which were presented at the second workshop "Computer Science Logic" held in Duisburg, FRG, October 3-7, 1988. These proceedings cover a wide range of topics both from theoretical and applied areas of computer science. More specifically, the papers deal with problems arising at the border of logic and computer science: e.g. in complexity, data base theory, logic programming, artificial intelligence, and concurrency. The volume should be of interest to all logicians and computer scientists working in the above fields.

The Voronoi diagram of a set of sites is a partition of the plane into regions, one to each site, such that the region of each site contains all points of the plane that are closer to this site than to the other ones. Such partitions are of great importance to computer science and many other fields. The challenge is to compute Voronoi diagrams quickly. The problem is that their structure depends on the notion of distance and the sort of site. In this book the author proposes a unifying approach by introducing abstract Voronoi diagrams. These are based on the concept of bisecting curves, which are required to have some simple properties that are actually possessed by most bisectors of concrete Voronoi diagrams. Abstract Voronoi diagrams can be computed efficiently and there exists a worst-case efficient algorithm of divide-and-conquer type that applies to all abstract Voronoi diagrams satisfying a certain constraint. The author shows that this constraint is fulfilled by the concrete diagrams based on large classes of metrics in the plane.

This book offers readers a broad view of research in some Western and Eastern European countries on pattern and signal analysis, and on coding, handling and measurement of images. It is a selection of refereed papers from two sources: first, a satellite conference within the biannual International Conference on Pattern Recognition held in Rome, November 14-17, 1988, and second, work done at the International Basic Laboratory on Image Processing and Computer Graphics, Berlin, GDR. The papers are grouped into three sections. The first section contains new proposals for the specific computation of particular features of digital images and the second section is devoted to the introduction and testing of general approaches to the solution of problems met in digital geometry, image coding, feature extraction and object classification. The third section illustrates some recent practical results obtained on real images specifically in character and speech recognition as well as in biomedicine. All the techniques illustrated in this book will find direct application in the near future. This book should interest and stimulate the reader, provoke new thoughts and encourage further research in this widely appealing field.

This monograph presents a novel execution model for the parallel execution of standard sequential Prolog. In this execution model Prolog procedure calls can be efficiently pipelined, and the author shows how even fully deterministic Prolog programs can be effectively mapped onto the proposed architecture. The design is based on a highly optimized abstract Prolog specific instruction set. A special feature of this work is a sophisticated classification scheme for Prolog variables which substantially reduces the overhead for unification with occur-check. To support the model an architecture consisting of a circular pipeline of independent processors has been designed. This pipeline has been designed to work as a co-processor to a UNIX based workstation. In contrast to other attempts to execute sequential Prolog in parallel, the proposed model does not restrict the use of any of the standard Prolog language features. The book gives a full account of the execution model, the system architecture, and the abstract Prolog instruction set.