This paper has been prepared under the EC TSER Programme's TIPIK Project, for pesentation to the 3 rd TIPIK Workshop held in Strasbourg, at BETA, University of Louis Pasteur, 24 th April 1999. We are grateful for the comments and suggestions received from colleagues in the TIPIK Project, although it has not been possible for all of those to be absorbed in the present version. Please do not reproduce or quote without permission of the authors. Contact authors at:

We use the term requirements to denote what are often called functional requirements. Requirements are located in the environment, which is distinguished from the machine to be built. A requirement is a condition over phenomena of the environment. A specifi-cation is a restricted form of requirement, providing enough information for the im-plementer to build the machine (by programming it) without further environment knowledge. To describe requirements appropriately we must fit our descriptions into an appropri-ate structure. This structure must respect the distinction between the machine and the environment, and the distinction between those environment properties that are given (indicative descriptions) and those that must be achieved by the machine (optative descrip-tions). Formalisation is a fundamental problem of requirements engineering. Since most en-vironments are parts of the physical world, and therefore informal, the formalisation task is inescapable. Some techniques are discussed for tackling this task. In particular, the use of designations is explained, and the distinction between definition and assertion. By using the smallest possible set of designated terms, augmented by appropriate defi-nitions, the developer can create a narrow bridge between the environment and its de-scriptions in the requirements. In this way a sufficiently faithful approximation to the informal reality can be obtained.

There is widespread anecdotal evidence that expert programmers make use of visual mental images when they are designing programs. This evidence is used to justify the use of diagrams and visual programming languages during software design. This paper reports the results of two studies. In the first, expert programmers were directly questioned regarding the nature of their mental representations while they were engaged in a design task. This investigative technique was used with the explicit intention of eliciting introspective reports of mental imagery. In the second, users of a visual programming language responded to a questionnaire in which they were asked about cognitive processes. The resulting transcripts displayed a considerable number of common elements. These suggest that software design shares many characteristics of more concrete design disciplines. The reports from participants in the two studies, together with previous research into imagery use, indicate potential...

In the MIT LEGO Robot Design Competition, students build robots that interact with their environmentÑthe contest playing Þeld, the game objects, and the opponent robot or robotsÑin particular ways. The robots thus become part of a complex system of interactions that deÞne their existence. In this paper I explore the biases that students bring to the task of designing their robots. Of particular interest is studentsÕ recurring inclination to build robots that will perform properly only under ideal conditions. Students repeatedly build robots that are not well-equipped to deal with the exigencies of the real world, but rather with the speciÞcations of an idealized, abstracted worldÑa world that the robot designers would like to believe is a close representation of reality, but is not. This result points to limitations in the set of ideas about technological systems and methods that comprise the core of the engineering curriculum. What surprises many participants is that these ideas do not map well to the challenge of designing a robot to play in one of our contests.

This paper explores the role of ‘virtual prototyping’ techniques, concepts and models in facilitating multi-functional processes co-ordination and multi-disciplinary knowledge integration. It argues that the role of software in supporting inter-functional co-operation and the co-ordination of knowledge and activities depends on the organisation’s ability to nurture integrating routines which support two-directional translation flows between ‘local ’ (function-based) and ‘global’ (computer-embedded) knowledge and activity levels. These mechanisms also lie at the heart of dynamic capabilities creation and maintenance.

The possibility of using freehand sketching as the language for interactive design is a longstanding goal. The ability to sketch a 3D object, predict its performance, and redesign it interactively using physics-based feedback would bring the power of state-of-the-art analysis tools into the critical, early design phase. The enormous potential of sketch-based interfaces is widely recognized, and has been broadly pursued. The practical use of such attempts has remained limited because these interfaces have been primarily 2D, loosing much of the benefit of mainstream 3D analysis potential. In order to become truly 3D, the spatial geometry must be automatically – and quickly – reconstructed from a single 2D sketch in near real-time. Once reconstructed, it can be converted into a model for simulation, and the simulation results interpreted back into the sketch. This paper presents a system that performs that reconstructs a 3D object from a freehand sketch, and uses the reconstructed object as the basis for a physical simulation. The system represents a first step towards fully interactive physics-based 3D design.

Visual programming languages aim to broaden the use of diagrams within the software industry, to the extent that they are integrated into the programming language itself. As a result, they provide an ideal opportunity to study the benefits of diagrams as an external representation during problem solving: not only is programming a challenging problem-solving activity, but the effect of diagram usage can be directly assessed by comparing performance while using a visual programming language to performance with a standard textual language. There have been several misconceptions amongst visual language researchers regarding the role of diagrams in software design, but these are being addressed by empirical studies and by new theories of notation design derived from studies of visual programming. Based on this research, the authors are able to recommend several new directions for research into thinking with diagrams. Keywords: diagrams, diagrammatic reasoning, visual programming, ...

Modern computer systems routinely present information to the user as a combination of text and diagrammatic images, described as "graphical user interfaces". Practitioners and researchers in Human-Computer Interaction (HCI) generally believe that the value of these diagrammatic representations is derived from metaphorical reasoning; they communicate abstract information by depicting a physical situation from which the abstractions can be inferred. This assumption has been prevalent in HCI research for over 20 years, but has seldom been tested experimentally. This thesis analyses the reasons why diagrams are believed to assist with abstract reasoning. It then presents the results of a series of experiments testing the contribution of metaphor to comprehension, problem solving, explanation and memory tasks carried out using a range of different diagrams. The results indicate that explicit metaphors provide surprisingly little benefit for cognitive tasks using diagrams as an external re...

It is a privilege and a great pleasure to join so many distinguished computer scientists in celebrating the work of Tony Hoare. Tony and I first met when

Reducing the physical distance among R&D engineers and between R&D and marketing is widely believed to result in more frequent communication, and hence higher product development performance. However, the empirical evidence for the effect of co-location on communication frequency is problematic for two reasons: (1) the evidence often features either little contextual realism or doubtful internal validity, and (2) the analysis does not deal with the statistical problems typical of network data. Our study avoids the first problem by using sequential network data collected from a quasi-experiment at an industrial company that regrouped its R&D teams into a new facility. We avoid the second problem by using Wasserman and Iacobucci's (1988) method for the statistical analysis of sequential network data. Our results show that communication among R&D teams was enhanced after co-locating these teams. Surprisingly, communication frequency between R&D and marketing was not affected by the increa...