Parallel Execution Of Logic Programs

Multiprocessor Execution of Logic Programs addresses the problem of efficient implementation of logic programming languages, specifically Prolog, on multiprocessor architectures. The approaches and implementations developed attempt to take full advantage of sequential implementation technology developed for Prolog (such as the WAM) while exploiting all forms of control parallelism present in logic programs, namely, or-parallelism, independent and-parallelism and dependent and-parallelism. Coverage includes a thorough survey of parallel implementation techniques and parallel systems developed for Prolog. Multiprocessor Execution of Logic Programs is recommended for people implementing parallel logic programming systems, parallel symbolic systems, parallel AI systems, and parallel theorem proving systems. It will also be useful to people who wish to learn about the implementation of parallel logic programming systems.

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?

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 is an updated version of my Ph.D. dissertation, The AND/OR Process Model for Parallel Interpretation of Logic Programs. The three years since that paper was finished (or so I thought then) have seen quite a bit of work in the area of parallel execution models and programming languages for logic programs. A quick glance at the bibliography here shows roughly 50 papers on these topics, 40 of which were published after 1983. The main difference between the book and the dissertation is the updated survey of related work. One of the appendices in the dissertation was an overview of a Prolog implementation of an interpreter based on the AND/OR Process Model, a simulator I used to get some preliminary measurements of parallelism in logic programs. In the last three years I have been involved with three other implementations. One was written in C and is now being installed on a small multiprocessor at the University of Oregon. Most of the programming of this interpreter was done by Nitin More under my direction for his M.S. project. The other two, one written in Multilisp and the other in Modula-2, are more limited, intended to test ideas about implementing specific aspects of the model. Instead of an appendix describing one interpreter, this book has more detail about implementation included in Chapters 5 through 7, based on a combination of ideas from the four interpreters.

Constraint Logic Programming (CLP), an area of extreme research interest in recent years, extends the semantics of Prolog in such a way that the combinatorial explosion, a characteristic of most problems in the field of Artificial Intelligence, can be tackled efficiently. By employing solvers dedicated to each domain instead of the unification algorithm, CLP drastically reduces the search space of the problem, which leads to increased efficiency in the execution of logic programs. CLP offers the possibility of solving complex combinatorial problems in an efficient way, and at the same time maintains the advantages offered by the declarativeness of logic programming. The aim of this book is to present parallel and constraint logic programming, offering a basic understanding of the two fields to the reader new to the area. The first part of the book gives an introduction to the fundamental aspects of conventional logic programming which is necessary for understanding the parts that follow. The second part includes an introduction to parallel logic programming, architectures and implementations proposed in the area. Finally, the third part presents the principles of constraint logic programming. The last two parts also include descriptions of the supporting facilities for the two paradigms in two popular systems; ECLIPSe and SICStus. These platforms have been selected mainly because they offer both parallel and constraint features. Annotated and explained examples are also included in the relevant parts, offering a valuable guide and a first practical experience to the reader. Finally, applications of the covered paradigms are presented. The authors felt that a book of this kind should provide some theoretical background necessary for the understanding of the covered logic programming paradigms, and a quick start for the reader interested in writing parallel and constraint logic programming programs. However it is outside the scope of this book to provide a deep theoretical background of the two areas. In that sense, this book is addressed to a public interested in obtaining a knowledge of the domain, without spending the time and effort to understand the extensive theoretical work done in the field – namely postgraduate and advanced undergraduate students in the area of logic programming. This book fills a gap in the current bibliography, since there is no comprehensive book of this level that covers the areas of conventional, parallel, and constraint logic programming. Parallel and Constraint Logic Programming: An Introduction to Logic, Parallelism and Constraints is appropriate for an advanced level course on Logic Programming or Constraints, and as a reference for practitioners and researchers in industry.

Covers the latest research in areas such as theoretical foundations, constraints, concurrency and parallelism, deductive databases,language design and implementation, non-monotonic reasoning, and logicprogramming and the Internet. 8-12 July 1997, Leuven, Belgium The International Conference on Logic Programming is the main annual conference sponsored by the Association for Logic Programming. It covers the latest research in areas such as theoretical foundations, constraints, concurrency and parallelism, deductive databases, language design and implementation, non-monotonic reasoning, and logic programming and the Internet.

This book introduces the parallel and distributed approach to logic programming, examining existing models of distributed logic programming, and proposing an alternative framework for distributed logic programming using extended Petri nets. The hardwired realization of the Petri net based framework is presented in detail, and principles of mapping of a logic program on to the proposed framework are outlined. Finally, the book explores the scope of Petri net models in designing next-generation deductive database machines.