Karsten Loer

Towards usable and relevant model checking techniques for the analysis of dependable interactive systems

Model checking is a formal technique for the automated analysis of system models against formal requirements. Once a suitable model and property have been specified, no further interaction by the analyst is required. However, this does not make the method necessarily user friendly since the checker must be provided with appropriate and complex input data. Furthermore, counter-examples generated by the system are often difficult to interpret. Because of this complexity, model checking is not commonly used, and exhaustive exploration of system models based on finite state descriptions is not exploited within industrial dependable systems design. The paper describes the development of an integrated collection of tools around SMV, intended to make it more accessible to practicing software engineers and in particular those concerned with the human interface issues in complex safety critical systems.

An integrated framework for the analysis of dependable interactive systems (IFADIS): Its tool support and evaluation

This paper discusses a method for the analysis of dependable interactive systems using model checking, and its support by a tool designed to make it accessible to a broader community. The method and the tool are designed to be of value to system engineers, usability engineers and software engineers. It has been designed to help usability engineers by making those aspects of the analysis relevant to them explicit while concealing those aspects of modelling and model checking that are not relevant. The paper presents the results of a user evaluation of the effectiveness of aspects of the tool and how it supports the proposed method.

Analysing user confusion in context aware mobile applications

Mobility of ubiquitous systems offers the possibility of using the current context to infer information that might otherwise require user input. This can either make user interfaces more intuitive or cause subtle and confusing mode changes. We discuss the analysis of such systems that will allow the designer to predict potential pitfalls before the design is fielded. Whereas the current predominant approach to understanding mobile systems is to build and explore experimental prototypes, our exploration highlights the possibility that early models of an interactive system might be used to predict problems with embedding in context before costly mistakes have been made. Analysis based on model checking is used to contrast configuration and context issues in two interfaces to a process control system.

Connecting Rigorous System Analysis to Experience-Centered Design

This chapter explores the role that formal modelling may play in aiding the visualization and implementation of usability, with a particular emphasis on experience requirements in an ambient and mobile system. Mechanisms for requirements elicitation and evaluation are discussed, as well as the role of scenarios and their limitations in capturing experience requirements. The chapter then discusses the role of formal modelling by revisiting an analysis based on an exploration of traditional usability requirements before moving on to consider requirements more appropriate to a built environment. The role of modelling within the development process is re-examined by looking at how models may incorporate knowledge relating to user experience, and how the results of the analysis of such models may be exploited by human factors and domain experts in their consideration of user experience issues.

Analysing Dynamic Function Scheduling Decisions

Function allocation, as a process used in the construction of dependable complex systems, is a significant aspect of the design and implementation of interactive systems. It involves a documented and rational process for deciding what aspects of the system should be controlled by which human roles in the system and how the system should be automated to support these roles effectively. As computer systems have become more advanced, and the control of systems more complex, the notion of dynamic function allocation becomes increasingly desirable where in certain situations the automation may take over or give back function to the human user. In this paper we explore a further variant of dynamic function allocation that reflects typical work activity where the dynamic scheduling of activities takes place on the time dimension. The paper discusses this approach to dynamic function allocation called dynamic function scheduling and discusses the role that timed model checking may play in helping identify dependable dynamic function scheduling solutions.

Time design: analysing human temporal control behaviour in dynamic real-time systems

This paper presents work aimed at supporting the design of temporal aspects of socio-technical systems. Time design is a framework for (a) analysing and representing temporal properties of the work domain, (b) generating design options that support timely, flexible and dependable function servicing, and (c) providing knowledge about the characteristics and biases of human temporal control behaviour. In support of the latter end, two microworld experiments that investigated temporal control decisions in a supervisory control task are presented. These experiments manipulated event rate, the duration of event rate blocks, the availability of online and offline event rate information, and the accuracy of this information. The studies identified conditions where attention to temporal information decreased and the use of conservative temporal control strategies increased