This volume contains selected papers presented at the Eighth Logic Programming Conference, held in Tokyo, 1989. Various topics in logic programming are covered. The first paper is an invited talk by Prof. Donald Michie, Chief Scientist of the Turing Institute, entitled "Human and Machine Learning of Descriptive Concepts", and introduces various research results on learning obtained by his group. There are eleven further papers, organized into sections on reasoning, logic programming language, concurrent programming, knowledge programming, natural language processing, and applications. A paper on knowledge programming introduces a flexible and powerful tool for incorporating and organizing knowledge using hypermedia. Another paper presents the constraint logic programming language cu-Prolog, designed for combinatorial problems; the way cu-Prolog solves the constraints is based on program transformation.

The present volume contains the proceedings of Logic at Botik '89, a symposium on logical foundations of computer science organized by the Program Systems Institute of the USSR Academy of Sciences and held at Pereslavl-Zalessky, USSR, July 3-8, 1989. The scope of the symposium was very broad; the topics of interest were: complexity of formal systems, constructive mathematics in computer science, denotational and operational semantics of programs, descriptive complexity, dynamic and algorithmic logics and schematology, formal tools to describe concurrent computations, lambda calculus and related topics, foundations of logic programming, logical foundations of database theory, logics for knowledge representation, modal and temporal logics, type theory in programming, and verification of programs. Thus, the papers in this volume represent many interesting trends in logical foundations of Computer Science, ranging from purely theoretical research to practical applications of theory.

This volume contains the proceedings of the Fifteenth Colloquium on Trees in Algebra and Programming. The papers selected present new research results and cover the following topics: - Logical, algebraic and combinatorial properties of discrete structures (strings, trees, graphs, etc.), including the theory of formal languages considered as that of sets of discrete structures and the theory of rewriting systems over these objects. - Application of discrete structures in computer science, including syntax and semantics of programming languages, operational semantics, logic programming, algorithms and data structures, complexity of algorithms and implementation aspects, proof techniques for nonnumerical algorithms, formal specifications, and visualization of trees and graphs.

The 18 research articles of this volume discuss the major themes that have emerged from mathematical and statistical research in the epidemiology of HIV. The opening paper reviews important recent contributions. Five sections follow: Statistical Methodology and Forecasting, Infectivity and the HIV, Heterogeneity and HIV Transmission Dynamics, Social Dynamics and AIDS, and The Immune System and The HIV. In each, leading experts in AIDS epidemiology present the recent results. Some address the role of variable infectivity, heterogeneous mixing, and long periods of infectiousness in the dynamics of HIV; others concentrate on parameter estimation and short-term forecasting. The last section looks at the interaction between the HIV and the immune system.