A formal methodology is presented for the systematic evolution of modular Standard ML programs from specifications by means of verified refinement steps, in the framework of the Extended ML specification language. Program development proceeds via a sequence of design (modular decomposition), coding and refinement steps. For each of these three kinds of steps, conditions are given which ensure the correctness of the result. These conditions seem to be as weak as possible under the constraint of being expressible as "local" interface matching requirements. Interfaces are only required to match up to behavioural equivalence, which is seen as vital to the use of data abstraction in program development. Copyright c fl 1989 by D. Sannella and A. Tarlecki. All rights reserved. An extended abstract of this paper will appear in Proc. Colloq. on Current Issues in Programming Languages, Joint Conf. on Theory and Practice of Software Development (TAPSOFT), Barcelona, Springer LNCS (1989)....

Extended ML is a framework for the formal development of programs in the Standard ML programming language from high-level specifications of their required input/output behaviour. It strongly supports the development of modular programs consisting of an interconnected collection of generic and reusable units. The Extended ML framework includes a methodology for formal program development which establishes a number of ways of proceeding from a given specification of a programming task towards a program. Each such step gives rise to one or more proof obligations which must be proved in order to establish the correctness of that step. This paper is intended as a user-oriented summary of the Extended ML language and methodology. Theoretical technicalities are avoided whenever possible, with emphasis placed on the practical aspects of formal program development. An extended example of a complete program development in Extended ML is included.

This paper is a survey of the current state of the art of research on methods for formal software development. The scope of this paper is necessarily restricted so as to avoid discussion of a great many approaches at a very superficial level. First, although some of the ideas discussed below could be (and have been) applied to hardware development as well as to software development, this topic will not be treated here. Second, the special problems involved in the development of concurrent systems will not be discussed here although again many of the approaches mentioned below could be applied in this context. Third, no attempt is made to treat programming methodologies such as Jackson's method and program development systems such as the MIT Programmer's Apprentice which are not formally based. Finally, this survey does not claim to be fully exhaustive although an attempt has been made to cover most of the main approaches. Many of the technical details of the different approaches discussed have been glossed over or simplified for the purposes of this presentation; full details may be found in the cited references.

. The walking-(and searching-) pattern generator of stick insects, a modular system composed of reflex chains and edogenous oscillators. Biological Cybernetics, 69:305-- 317, 1993. [12] Francoise Beaufays and Eric A. Wan. Relating real-time backpropagation and backpropagation-through-time: An application of flow graph interreciprocity. Neural Computation, 6:296--306, 1994. [13] Randall D. Beer. Intelligence as Adaptive Behavior: An Experiment in Computational Neuroethology. Academic Press, 1990. 211 212 BIBLIOGRAPHY [14] Randall D. Beer, Hillel J. Chiel, Roger D. Quinn, Kenneth S. Espenschied, and Patrick Larsson. A distributed neural network architecture for hexapod robot locomotion. Neural Computation, 4:356--365, 1992. [15] Randall D. Beer, Hillel J. Chiel, and Leon S. Sterling. An artificial insect. American Scientist, 79:444--452, 1991. [16] Geoffrey Black. Control of an overhe

This document contains the annotated VDM bibliography with more than 600 entries related to VDM. The listed items come from a wide variety of sources, but unfortunately the list is not yet exhaustive. This version contains a partitioning of entries into categories of subjects. A little introduction and background material is given, and some advice on how to get started with VDM (for newcomers). This document was previously edited at the Technical University of Denmark by Dines Bjørner (subject editor) and Annie Rasmussen (copy editor). The editor regrets that he is unable to supply hard copy of items referenced in the bibliography. Document History Zero'eth version of this document issued on 19. March 1987. Printed in 200 copies. Some 150 distributed, courtesy DDC, at the CEC VDM-Europe Symposium '87: VDM: A Formal Method at Work, March, 1987, Brussels. The first version was distributed at the CEC VDM-Europe Symposium '88: VDM --- The Way Ahead, September 1988, Dublin. The second ve...