Using Transformations in Specification-Based Prototyping.

We explore the use of software transformations for software evolution. Meaning-preserving program transformations have been widely used for program development from a fixed initial specification. We consider a wider class of transformations to support development in which the specification evolves, rather than being fixed in advance. We present a new and general classification of transformations based on their effect on system interfaces, externally observable behavior, and abstraction level of a system description. This classification is used to rearrange chronological derivation sequences containing meaning-changing transformations into lattices containing only meaning-preserving transformations. This paper describes a process model for software evolution, utilizing prototyping techniques, and shows how this class of transformations can be used to support such a process. A set of examples illustrates our ideas. Software tool support and directions for future research are discussed. [ABSTRACT FROM AUTHOR]