Abstract A lightweight role‐based access control policy authoring tool was developed for e‐Scientists, a community for which access policies have to be implemented for an increasingly heterogeneous group of local and remote users. Two fundamental problems were identified: (1) lack of understanding of what the policy components are (i.e. how authorization policies are structured), and (2) lack of understanding of the underlying policy paradigm (i.e. what should go into the policy, and what should be left out). Conceptual design (CD) techniques were used to revise the user interface (UI) labels so that e‐Scientists and developers were better able to describe access policy components from labels, and match labels with components (t = 6.28, df = 7, p = 0.000 two‐tailed). CD, instructional text, bubble help, UI behaviour and alert boxes were used to shape users' models of the policy paradigm. The final prototype improved users' efficiency and effectiveness by more than doubling the speed with which expert users could write authorization policies, and facilitating users without specialist security knowledge to overcome the policy paradigm and components problems, enabling them to complete 80% of basic and 75% of advanced authorization policy‐writing tasks in a usability trial. Copyright © 2005 John Wiley & Sons, Ltd.

Abstract A suite of software tools for the manipulation and validation of first‐order logic expressions is presented. The suite ponsists of a collection of modules, each performing a precise and well‐defined task. More sophisticated tasks such as theorem proving can be achieved by concatenating modules and interacting at suitable stages.

Abstract The concept of an invariant assertion has been shown by Hoare to be central to the problem of proving correctness of data representation in a program. A consequent approach for program design is to establish the parts of an overall invariant which characterize the components of the design. In this way it is feasible to synthesize a verified program. There is a gulf between verification theory and practical reality in this area, but the SIMULA class concept is close to the data representation technique required for such an approach. Some of the benefits and problems of this approach to design have been explored by the development of a SIMULA program to simulate a bounded delay resource allocation strategy in a job scheduling environment.

Abstract The GLIDE system is an effectively language‐independent aid of modest proportions for developing programs by stepwise refinement. The basis of the system is a suitable program file environment The system has been implemented on the Imperial College Computer Centre Control Data machine and is currently available for the development of programs written in PASCAL, ALGOL, FORTRAN, SIMULA and JCL (Job Control Language). The program itself is written in PASCAL The facilities obtained within the scope and limitations of the system conception suggest that this type of system could be given further attention.