Technical Report CS0561

Title: Why A Single Parallelization Strategy is Not Enough in Knowledge Bases
Authors: S. Rabinovici Cohen and O. Wolfson
Abstract: We argue that the appropriate parallelization strategy for logic-program evaluation depends on the program being evaluated. Therefore, this paper is concerned with the issues of program classification, and parallelization-strategies. We propose several parallelization strategies based on the concept of data-reduction - the original logic-program is evaluated by several processors working in parallel, each using only a subset of the database. The strategies differ on the evaluation cost, the overhead of communication and synchronization among processors, and the programs to which they are applicable. In particular, we start our study with pure-parallelization, i.e., parallelization without overhead. An interesting class-structure of logic programs is demonstrated, when considering amenability to pure-parallelization. The relationship to the NC complexity class is demonstrated. Then we propose strategies that do incur an overhead, but are optimal in a sense that will be precisely defined. This paper makes the initial steps towards a theory of parallel logic-programming.
CopyrightThe above paper is copyright by the Technion, Author(s), or others. Please contact the author(s) for more information

Remark: Any link to this technical report should be to this page (, rather than to the URL of the PDF files directly. The latter URLs may change without notice.

To the list of the CS technical reports of 1989
To the main CS technical reports page

Computer science department, Technion