Epia 91

The Portuguese Association for Artificial Intelligence has been organizing Portuguese Conferences on Artificial Intelligence, now held every second year, since 1985. This volume contains selected papers from the Fifth Conference on Artificial Intelligence. The conference has an international status: 62 contributions from 13 countries were received, of which 26 were from Portugal. To guarantee a high scientific standard, all the contributions were reviewed by at least three researchers,and only 20 papers were accepted and included in these proceedings. The papers are organized into sections on constraints, search, knowledge representation, temporal reasoning, planning, diagnosis and repair, and learning.

Logic programming refers to execution of programs written in Horn logic. Among the advantages of this style of programming are its simple declarativeand procedural semantics, high expressive power and inherent nondeterminism. The papers included in this volume were presented at the Workshop on Parallel Logic Programming held in Paris on June 24, 1991, as part of the 8th International Conference on Logic Programming. The papers represent the state of the art in parallel logic programming, and report the current research in this area, including many new results. The three essential issues in parallel execution of logic programs which the papers address are: - Which form(s) of parallelism (or-parallelism, and-parallelism, stream parallelism, data-parallelism, etc.) will be exploited? - Will parallelism be explicitly programmed by programmers, or will it be exploited implicitly without their help? - Which target parallel architecture will the logic program(s) run on?

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.

In the past decade, the formal theory of specification, verfication and development of real-time programs has grown from work of a few specialized groups to a real "bandwagon". Many eminent research groups have shifted their interests in this direction. Consequently, research in real-time is now entering established research areas in formal methods, such as process algebra, temporal logic, and model checking. This volume contains the proceedings of a workshop dedicated to the theory of real-time with the purpose of stepping back and viewing the results achieved as well as considering the directions of ongoing research. The volume gives a representative picture of what is going on in the field worldwide, presented by eminent, active researchers. The material in the volume was prepared by the authors after the workshop took place and reflects the results of the workshop discussions.

This volume presents the proceedings of the first French-Soviet workshop on algebraic coding, held in Paris in July 1991. The idea for the workshop, born in Leningrad (now St. Petersburg) in 1990, was to bring together some of the best Soviet coding theorists. Scientists from France, Finland, Germany, Israel, Italy, Spain, and the United States also attended. The papers in the volume fall rather naturally into four categories: - Applications of exponential sums - Covering radius - Constructions -Decoding.

This book presents state-of-the-art research results in the area of formal methods for real-time and fault-tolerant systems. The papers consider problems and solutions in safety-critical system design and examine how wellthe use of formal techniques for design, analysis and verification serves in relating theory to practical realities. The book contains papers on real-time and fault-tolerance issues. Formal logic, process algebra, and action/event models are applied: - to specify and model qualitative and quantitative real-time and fault-tolerant behavior, - to analyze timeliness requirements and consequences of faulthypotheses, - to verify protocols and program code, - to formulate formal frameworks for development of real-time and fault-tolerant systems, - to formulate semantics of languages. The integration and cross-fertilization of real-time and fault-tolerance issues have brought newinsights in recent years, and these are presented in this book.

This volume contains papers presented at the first international workshop onword equations and related topics held at the University of T}bingen in October 1990. Word equations, the central topic of this annual workshop, lieat the intersection of several important areas of computer science, suchas unification theory, combinatorics on words, list processing, and constraint logic programming. The workshop is a forum where researchers fromthese different domains may present and discuss results and ideas, thereby supporting interaction and cross-fertilization between theoretical questions and practical applications. The volume collects papers which: - contain new and relevant results, - describe a new approach to a subject, or - give a survey of main developments in an area. Papers cover investigations on free groups, associative unification and Makanin's algorithm to decide the solvability of equations in free semigroups, general unification theory and its relationship to algebra and model theory, Thue systems, and finitely presented groups.

This volume gives the proceedings of the ninth Symposium on Theoretical Aspects of Computer Science (STACS). This annual symposium is held alternately in France and Germany and is organized jointly by the Special Interest Group for Fundamental Computer Science of the Association Francaise des Sciences et Technologies de l'Information et des Syst mes (AFCET) and the Special Interest Group for Theoretical Computer Science of the Gesellschaft f}r Informatik (GI). The volume includes three invited lectures and sections on parallel algorithms, logic and semantics, computational geometry, automata and languages, structural complexity, computational geometry and learning theory, complexity and communication, distributed systems, complexity, algorithms, cryptography, VLSI, words and rewriting, and systems.