A note on abstraction in software descriptions

Abstract

In the process of software development, abstraction is usually treated as a mere change of scale. Therefore, the only widely used principle for changing the level of abstraction is a change in quantity, for instance by stepwise refinement. This paper is based on the observation that there are in fact more differences between descriptions at different levels. Two consequences are suggested: first, an extended Entity-Relationship-Model, and second, a set of abstraction levels, each related to a specific "filter" through which the system is seen. The paper is prefaced by a remark on terminology and by some information on my background.