Studies related to the process of program development

The submitted work consists of a collection of publications arising from research carried out at Rhodes University (1970-1980) and at Heriot-Watt University (1980-1992). The theme of this research is the process of program development, i.e. the process of creating a computer program to solve some particular problem. The papers presented cover a number of different topics which relate to this process, viz. (a) Programming methodology programming. (b) Properties of programming languages. aspects of structured. (c) Formal specification of programming languages. (d) Compiler techniques. (e) Declarative programming languages. (f) Program development aids. (g) Automatic program generation. (h) Databases. (i) Algorithms and applications

Prolog and deductive databases

The logic programming language Prolog has been shown to be a very suitable language for implementing database concepts. However, current Prolog implementations are limited, and the database examples used have all consisted of relatively small sets of clauses. The reason for this is that existing Prolog implementations do not scale up to handle large databases. This paper describes a project whose aims are to develop the links between logic programming and databases. The prime aim is to develop a Prolog system which is capable of handling large sets of clauses. The second aim is to implement a deductive database management system in Prolog, while a third is to evaluate the effectiveness of parallel logic languages for implementing database applications. Ke ywords: Prolog, Parlog, logic programming, deductive databases Within the field of database systems several different approaches have been used, but of these the relational database has emerged as the most popular. The clean, uniform approach of the relational data model, and the power and simplicity of relational query languages have been the main reasons for the success of relational databases. These, in their turn, owe much to logic, as the relational calculus is a restricted form of first order predicate calculus. With the growth of interest in knowledge processing, and in expert systems in particular, a need has been developing for more powerful database systems- systems which can store and retrieve knowledge; such systems are generally referred to as ’knowledge base management’ systems, or ’expert database ’ systems. One of the formalisms used for representing knowledge is first order predicate calculus. In view of the role of logic in underpinning relational databases and in describing knowledge, a natural successor to relational database systems, in the form of logic or deductive databases, has been proposed. Such systems are natural extensions of relational databases based on a more general form of first order logic. One particular form, known as a definite deductive database, has been studied in some detail1. This form of database i