The paper introduces a novel algorithm for the location-awareness problem of estimating symbolic user location for indoor spaces using IEEE 802.11 (Wi-Fi) wireless signals. The characteristic of the problem is that the signals fluctuate greatly, not only across perturbations in space, but also in time (diurnally), which leads to poor location estimation. The /spl eta/k-nearest neighbour (/spl eta/k-NN) algorithm is an instance-based learning algorithm which normalizes the sample data set of the Wi-Fi signal strength and signal quality to achieve the maximum correct result of symbolic user location at a room scale. Data normalization is found to play an important role in determining the quality of the training data-set which has direct impact on the estimation result. The algorithm has been compared to other k-nearest neighbour (k-NN) and shows promising results.

First order logic provides a means of integrating the specification and prototyping of interactive systems. It can describe graphical images in a declarative and order independent manner. It supports the definition of abstract devices which avoid the complexity of representing ‘raw’ input from a variety of physical devices. The following pages show how such techniques must be extended in order to prototype and reason about dynamic interaction with graphical interfaces. The incorporation of a temporal ordering into logical specifications provides a means of describing changes in the structure of graphical images. It can also identify the sequencing which may be implicit within specifications of interactive dialogues. This paper describes how PRELOG, a tool for Presenting and REndering LOGic specifications of interactive systems, has been extended to include a temporal logic interpreter.

Formal specifications provide the non-specialist with an extremely poor impression of what it would be like to interact with a computer system. Prototypes provide a far better impression of the ‘look and feel’ of possible implementations but lack the precision of more formal approaches. Unfortunately, specification and prototyping are typically treated as alternatives. If these two activities can be harnessed then the designer has a means of incorporating the user into systems design. Tools can ease the transition from specification to prototype by supporting the visualisation of a design in terms of graphical representations of the proposed system. This paper describes Prelog, a tool for Presenting and REndering LOGic specifications of interactive systems. Prelog supports the structured representation of interaction objects which describe virtual devices. Interaction objects support reasoning about prototypes because they provide a means of abstracting away from device dependent pragmatics which make renderings intractable.