Relation Algebra as programming language using the Ampersand compiler

Relation Algebra can be used as a programming language for building information systems. This paper demonstrates the principle by presenting a case study together with the theory behind programming in Relation Algebra. As a case study, we have developed a database application for legal reasoning. We discuss a small part of it to illustrate the mechanisms of programming in Relation Algebra. Beside being declarative, relation algebra comes with attractive prospects for developing software. The compiler that was used for this case study, Ampersand, is the result of an open source project. Ampersand has been tried and tested in practice and is available as free open source software.1