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Making systems easier to use implies an ever increasing complexity in managing communication between users and applications. Indeed an increasing part of the application code is devoted to the user interface portion. In order to manage this complexity, it is important to have tools, notations, and methodologies which support the designer’s work during the refinement process from specification to implementation. Selected revised papers from the Eurographics workshop in Namur review the state of the art in this area, comparing the different existing approaches to this field in order to identify the principle requirements and the most suitable notations, and indicate the meaningful results which can be obtained from them.



Invited Talks

Retrospective and Challenges for Model-Based Interface Development

Research on model-based user interface development tools is about 10 years old. Many approaches and prototype systems have been investigated in universities and research laboratories around the world. This paper proposes a generic architecture for these tools, reviews the different approaches in light of this architecture, and discusses their progress towards the goals of increasing the quality and reducing the cost of developing interfaces. The paper closes with a discussion of challenges for future model-based development tools.
Pedro Szekely

Human Factors in Aeronautics

In this paper, we will discuss the human factors that must be taken into account in aeronautics, concentrating on the technological evolution this sector is undergoing and the cognitive demands which are therefore put on pilots. This will oblige us to clearly define the status of human error and to understand its processes, as well as the phenomena of judgment and causal attribution by which it is marked. We will also analyze the question of how error is corrected within the framework of established technical systems. Finally, the predictability and, therefore, the certification of such technical systems will be questioned.
V. De Keyser, D. Javaux

Abstract Interpretation and Application to Interactive System Verification

Interpretation is widely known as a methodology for building static analyses of programs and is mainly used for program optimization; it can also be used for verification and is thus of interest for interactive system verification. The aim of this paper is twofold: Firstly, a survey of the methodology of abstract interpretation is presented; secondly, some favourite formalisms and notations from the interactive system verification area axe reviewed at light of abstract interpretation. We argue that systematic use of abstract interpretation in interactive system verification could help improving and unifying current techniques.
Baudouin Le Charlier

Moving Towards Implementation

Device Models

Previous work on characterising the variety of interaction devices has focused either on physical properties of the devices or the range of behaviours that they can invoke. This work sets out a new approach to evaluating the usability of devices, one that accounts for the cognitive resources needed to use the device to perform particular tasks. The framework draws its expressive power from a technique called syndetic modelling that allows the description of both the device and cognitive resources to be captured in a common representation. In this paper syndesis provides a foundation for examining the coordinate spaces and transformations that are needed both by the operator and the computer system in performing tasks with a given device.
G. P. Faconti, D. J. Duke

A Formal Description of Low Level Interaction and its Application to Multimodal Interactive Systems

The lack of formal models for describing low-level interaction restricts programmers to interactors provided by toolkits. It impedes the construction of highly interactive systems and the design of new interaction styles, such as multimodal interaction. This article reports on our experience with formalising low-level graphical interaction. We propose primitives for event specification and handling that can be used along with Petri nets to model such interactions. We then show how multimodal interactions can be built from monomodal ones by combining those models. This is exemplified by an experimental two-handed graphical editor that has been built using the proposed model.
Johnny Accot, Stéphane Chatty, Philippe Palanque

Deriving a formal model of an interactive system from its UIL description in order to verify and to test its behaviour

This paper focuses on verifying and testing the interaction or dialogue between a user and an interactive system, especially in case of safety critical systems. In order to verify that the interface of a system behaves as intended by the user, we based our ongoing research on a compromise by allowing the use of informal (but practical) and formal methods. In fact, a formal description of the user’s interests and activities through the Interface seems very hard to produce by common designers. A more realistic attitude consists in deriving a formal model from the description of the intended interface as it was informally designed. Practically, a tool generates models in the language Lustre from a user’s UIL description and these models are used for verification or test purposes.
Bruno d’Ausbourg, Guy Durrieu, Pierre Roche

Prototyping Device Interfaces with DSN/2

The specification language DSN/2 and the corresponding tool KAP are presented in this paper. They are designed for prototyping user interfaces of electronical technical devices, such as answering machines, CD players, or VCRs. The language DSN/2 is used to specify the control model of the user interface, including sound effects and timing conditions. The tool KAP adds a visual component to this abstract specification and allows editing, debugging, and end user testing with the defined model. Using this tool set, the designer of a user interface is enabled to create a realistic looking, sounding, and “feeling” model of the system under construction without the need of programming. In practical experience, the system was found suitable for performing user tests on the software model of a CD player. The results were verified against user testing on the real device.
Gerd Szwillus, Klaus Kespohl

Evaluating Formal Languages

Toward more understandable user interface specifications

Many different methods have been used to specify user interfaces: algebraic specification, grammars, task description languages, transition diagrams with and without extensions, rule-based systems, and by demonstration. However, none of these methods has been widely adopted. Current user interfaces are still built by writing a program, perhaps with the aid of a UIMS. There are two principal reasons for this. First, specification languages are difficult to use. Reading a specification and understanding its exact meaning is very difficult. Writing a correct specification is even more difficult. Second, most specification languages are not executable. This means that after the user interface programmer makes the effort to write a specification, the user interface must still be coded. As a consequence, most programmers have little incentive to do a specification. A pilot study into the comprehensibility of specifications is described. The results of this study suggest that user interface specifications are difficult to interpret manually. A possible solution to this problem, specification animation, is also described.
David A. Carr

Towards an integrated proposal for Interactive Systems design based on TLIM and ICO

The importance of applying formal methods in the design and development process of Interactive Systems is increasingly recognised. However it is still an open issue the identification of systematic methods able to support designers and developers in specifying and demonstrating properties of user interfaces. TLIM and ICO are two formal methods which have been used for this purpose with interesting results. They address similar concepts but also have different features which allow us to consider useful their integrated use to obtain synergistic and complementary results. In this paper we show their application to some examples in order to discuss similarities and differences and we outline a proposal for their integrated use.
Philippe Palanque, Fabio Paterno, Rémi Bastide, Menica Mezzanotte

The Evaluation Of User Interface Notations

Over the last decade a wide range of graphical, tabular and textual notations have been proposed to support the design of human-computer interfaces. These notations are intended to strip away the clutter of implementation details that frequently obscure interaction properties. Unfortunately, relatively little work has been done to evaluate the usability of these notations for ‘real-world’ interfaces. We have, therefore, conducted an empirical evaluation of the User Action Notation (UAN), State Transition Networks (STN) and temporal logic ‘in the wild’. By this we mean that our subjects were drawn from realistic samples of users and designers. We also presented our subjects with realistic descriptions of two user interfaces. This avoids a weakness of previous investigations that have used ‘toy examples’. The results of our investigation show a strong preference amongst our subjects for the use of natural language descriptions. More surprisingly, our results also suggest a link between the frequency of comprehension errors and positive attitude statements towards particular notations. In other words, our subjects made most errors with the notations that they liked the best. This suggests that while graphical notations, such as state transition networks, have a strong intuitive appeal they may also create significant problems for real-world development tasks.
Chris Johnson

Analysing Errors

Supporting Error-Driven Design

This paper argues that two limitations restrict the utility of interface specification languages. Firstly, they provide no means of capturing the cognitive conditions that lead to operator ‘error’. This makes it difficult to distinguish between the normal behaviour of an expert and the mistakes that often lead to problems for novices. The second weakness is that interface notations cannot easily be used to represent and reason about asynchronous failures. This prevents designers from identifying solutions to failures that could occur at many different points during interaction. These are significant limitations because they reflect a pre-occupation with normative behaviour. Unless we have some means of analysing system failure and operator error then we will continue to have interfaces that are designed to support perfect users in perfect environments.
Chris Johnson, Phil Gray

Risk Analysis, Impact and Interaction Modelling

Operator error has been blamed for many accidents and incidents in safety-critical systems. It is important that human-machine interface (HMI) designers are aware of the relationships between their design decisions, operator errors, and the hazards associated with a system. In this paper, we demonstrate how information from risk analysis can be combined with formal specification of the HMI, to support designers in exploring these relationships. We use the concept of interactor to model the human-machine interface (HMI); together with a concept of impact, which we define informally as: “the effect that an action or sequence of actions has on the safe and successful operation of a system.” We show how interactors can be used as design representations for the HMI at the earliest stages of design, as well as providing a medium by which risk analysts can inform HMI designers about the impact of human-errors. To demonstrate the feasibility of this approach, we consider a simple, gas-fired, electricity generating plant as a case study. Our proposed approach is intended to complement, rather than compete with, existing design and analysis methods for the HMI. The method achieves this by making risk analysis information available in the early stages of HMI design.
A. M. Dearden, M. D. Harrison

Design assistance for user-adapted interaction

This paper discusses current approaches to user interface adaptation and describes how some of their shortcomings can be overcome by supporting the articulation of user interface adaptation constituents during the early phases of design and development of a user interface. It is claimed that this type of adaptation support is required to ensure accessibility of a user interface by different user groups with varying abilities, requirements and preferences. Additionally, the paper describes the components of a prototype design environment called USE-IT which has been developed to support the automatic derivation of such adaptation decisions so as to ensure that the resulting user interface will be accessible by the target user (group). The tool is part of a novel user interface development platform which integrates design assistance and development support to provide a unifying basis for constructing high quality user interfaces that are accessible by different user groups, including disabled and elderly people.
D. Akoumianakis, A. Savidis, C. Stephanidis

Design, Specification and Verification

GRALPLA: An Algebraic Specification Language for Interactive Graphic Systems

The specification of interactive graphic systems involves the use of formal methods to describe the synchronization restrictions and graphic information. Several proposals have been made trying to join formalisms for the specification of concurrent systems with some methods to describe the graphic component. This paper presents an algebraic specification language which has been designed to specify interactive graphic systems. The language is founded on the use of a mathematical formalism to describe the graphic component, with an extension of algebraic specification language to describe synchronization, using guarded operations. The language is an extension of the previous Gralpla language, to which new features have been added to allow the specification of dynamic changes of the graphic representations and of processes. A prototyping tool has been defined for the language to generate C++ prototypes of the specifications.
J. C. Torres, M. Gea, F. L. Gutierrez, M. Cabrera, M. Rodriguez

Fusion Engines and Melting Pots

Emerging multi-modal technology relies on innovative techniques for managing data, both at the user interface level, and at the internal application level. To assess design alternatives for this class of system, it is desirable to have models that focus attention on the critical features of these systems. Formal methods of software specification are known to provide this abstractive power in many contexts. This paper shows that an established specification technique can be used profitably to model, assess and improve the design of a generic kernel for multimodal systems.
J. K. Hyde, D. J. Duke

Monolingual, Articulated Modeling of Users, Devices, and Interfaces

This paper presents a framework for combining the discrete models of users and devices into a global system model suitable for analysis and simulation. It views a system as a composite of interacting subsystems, and describes how those subsystems must be structured to permit compositions in which responsibility for global behavior can be appropriately ascribed. The paper presents a human-device example (wrist watch) and develops a range of task and device models. The devices and tasks are modeled by colored Petri nets partitioned to cleanly distinguish submodel component visibility and interface affordances. The formality of Petri nets allows for axiomatic validation of isolated and interacting subsystems.
Thomas Moher, Victor Dirda, Rémi Bastide, Philippe Palanque

Evaluating the Interfaces of Three Theorem Proving Assistants

A first step in systematically engineering better interfaces for theorem proving assistants (TPAs) is to assess what has already been achieved in the domain. We examine three TPAs employing quite different styles of interaction. We consider the support provided by the interfaces for each of four mechanisms for efficient interactive proof: planning, reuse, reflection and articulation. Common themes are observed, as are strengths and weaknesses of the interfaces and we discuss the general issues, attempting to abstract away from the particular artifacts studied.
Nicholas A. Merriam, Michael D. Harrison

Validating Properties of Component-based Graphical User Interfaces

In this paper we describe a validation process for graphical user interfaces based on existing toolkits and higher-order logic as mechanized in the HOL system. The underlying approach uses a single specification for constructing both implementations (prototypes) for experimentation and models for formal reasoning. The formal models allow the designer to verify mechanically specific requirements imposed on the user interface such as those found in safetyor security-critical applications. We illustrate our approach with an example that shows how the proof process works for behavioral properties that have been expressed in a rule-based fashion.
Peter Bumbulis, P. S. C. Alencar, D. D. Cowan, C. J. P. Lucena

Specifying and Reasoning About CSCW

In this paper we introduce a pair of logics which, taken together, can be seen as a first step towards a formal specification language for CSCW systems. We show the development of the logics and give some simple examples of their use. We also make a distinction between the computational part of the system and the people, i.e. we do not follow a simple action and agent analysis. Since people bring knowledge to a system we treat them differently. We also propose the use of situation theory as a way of capturing requirements.
Steve Reeves
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