The more obvious and well known drawbacks of using refinement as the sole means of progressing from an abstract model to a concrete implementation are reviewed. Retrenchment is presented in a simple partial correctness framework as a more flexible development concept for formally capturing the early otherwise preformal stages of development, and briefly justified. Given both a retrenchment of a...

ING REFINEMENTS FOR TRANSFORMATION EINAR BROCH JOHNSEN University of Oslo, Department of Informatics P.O. Box 1080 Blindern, N-0316 Oslo, Norway [email protected] CHRISTOPH LÜTH Universität Bremen, FB 3 — Mathematik und Informatik P.O. Box 330 440, D-28334 Bremen, Germany [email protected] Abstract. Formal program development by stepwise refinement involves a lot of work discharging ...