Much of the work on developing program transformation systems has concentrated on systems to assist in program development. However, the four separate surveys carried out between 1977 and 1990 (Foster and Kiekuth, 1990; Lientz and Swanson, 1980; Morton, 1988; Nosek and Palvia, 1990), summarized in Foster (1991), show that between 40% and 60% of all commercial software effort is devoted to software maintenance rather than the development of new systems. In this paper we describe a joint project between the University of Durham and CSM Ltd to develop a method and tool for reverse‐engineering and software maintenance based on program transformation theory. We present an example which illustrates how such a tool can extract a high‐level abstract specification from the low‐level source code of a program by a process of formal program transformation based on a theory of program equivalence (Ward, 1989a). All the code‐level reverse‐engineering of the example program was carried out on the prototype tool with the resulting code pasted directly into the paper.

The FermaT transformation system, based on research carried out over the last twelve years at Durham University and Software Migrations Ltd., is an industrial-strength formal transformation engine with many applications in program comprehension and language migration. This paper describes one application of the system: the migration of IBM 370 Assembler code to equivalent, maintainable C code. We present an example of using the tool to migrate a small, but complex, assembler module to C with no manual intervention required. We briefly discuss a mass migration exercise where 1,925 assembler modules were sucessfully migrated to C code.

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The aim of this paper is to provide a unified mathematical framework for program slicing which places all slicing work, for sequential programs, on a sound theoretical foundation. The main advantage to a mathematical approach is that it is not tied to a particular representation. In fact the mathematics provides a sound basis for any particular representation. We use the WSL (Wide Spectrum Language) program transformation theory as our framework. Within this framework we define a new semantic relation, semi-refinement which lies between semantic equivalence and semantic refinement. Combining this semantic relation, a syntactic relation (called reduction) and WSL's remove statement, we can give mathematical definitions for backwards slicing, conditioned slicing, static and dynamic slicing and semantic slicing as program transformations in the WSL transformation theory. A novel technique of "encoding" operational semantics within a denotational semantics allows the framework to handle "operational slicing". The theory also enables the concept of slicing to be applied to nondeterministic programs. These transformations are implemented in the industry-strength FermaT transformation system.

In this paper we consider a particular class of algorithms which present certain di culties to formal veri cation. These are algorithms which use a single data structure for two or more purposes, which combine program control information with other data structures or which are developed as a combination of a basic idea with an implementation technique. Our approach is based on applying proven semantics-preserving transformation rules in a wide spectrum language. Starting with a set theoretical speci cation of \reachability" we are able to derive iterative and recursive graph marking algorithms using the \pointer switching" idea of Schorr and Waite. There have been several proofs of correctness of the Schorr-Waite algorithm, and a small number of transformational developments of the algorithm. The great advantage of our approach is that we can derive the algorithm from its speci cation using only general-purpose transformational rules: without the need for complicated induction arguments. Our approach applies equally well to several more complex algorithms which make use of the pointer switching strategy, including a hybrid algorithm which uses a xed length stack, switching to the pointer switching strategy when the stack runs out.

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In this paper we give a brief introduction to the foundations of WSL transformation theory and describe some applications to program slicing. We introduce some generalisations of traditional slicing, amorphous slicing and conditioned slicing which are possible in the framework of WSL transformations. One generalisation is "semantic slicing" which combines slicing and abstraction to a specification.

Reports results of a questionnaire survey of 27 Principal Engineers at Ricardo Consulting Engineers, a leading powertrain consultancy, dedicated to the design, testing and research of engines and transmissions, conducted in 1996-1997. The study investigated the degree to which these engineers use informal information sources, such as colleagues, and formal sources, such as their own and their departments’ collections of notes and other literature, and Ricardo’s Information Services Department (ISD), in particular its large textbase of engineering references, POWERLINK. Takes a humanist viewpoint to provide insights into the culture of a leading engineering company and the working lives of its engineers through a study of their need for and use of information, in relation to their biography, their cognitive style, and attitudes to work. A wide range of patterns of library use were revealed: ten respondents visited the library more than once a week; two claimed to be very frequent visitors; eight others claimed to use it about once a week; three said their visits followed no set patterns. The most popular reason for using the library was to consult the database but an objective test of six retrieval methods revealed a severe lack of understanding of basic retrieval techniques, which seemed to conflict with the general attitude of the engineers. Concludes by examining the values underlying the data, such as time, personality, information and communication, as a way of organizing the survey’s findings.