Multiple points of view in modelling programs

An important issue discussed at the workshop on data abstraction is the need to represent multiple, overlapping points of view and relationships between them. The first two sections of this paper motivate the use of multiple and overlapping points of view in modelling programs and data structures. The final section of the paper briefly describes a new formalism, called overlays, which has been developed for this purpose, and which may be of general interest. The overall goal of the research from which this paper is drawn is to compile a library of standard, generally used data and control abstractions to be used in the interactive analysis, synthesis and verification of programs. Multiple points of view were needed in this context is in order to decompose the data and control structures of users' programs in a way which makes explicit their relationship to the library of standard abstractions.