Abstract
This paper presents a new approach in plant modeling for the formal verification of real time systems. A system composed by two tanks is used, where all its components are modeled by simple modules and all the interdependences of the system's modular models are presented. As innovating parameters in the plant modeling, having as purpose its use on formal verification tasks, the plant is modeled using Dymola software and Modelica programming language. The results obtained in simulation are used to define the plant models that are used for the formal verification tasks, using the model-checker UPPAAL. The paper presents, in a more detailed way, the part of this work that is related to formal verification, being pointing out the used plant modeling approach. © 2007 IFAC.

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Abstract
Internet accessibility for the visually impaired community is still an open issue. Guidelines have been issued by the W3C consortium to help web designers to improve web site accessibility. However several studies show that a significant percentage of web page creators are still ignoring the proposed guidelines. Several tools are now available, general purpose, or web specific, to help visually impaired readers. But is reading a web page enough? Regular sighted users are able to scan a web page for a particular piece of information at high speeds. Shouldn't visually impaired readers have the same chance? This paper discusses some features already implemented to improve accessibility and presents a user feedback report regarding the AudioBrowser, a talking browser. Based on the user feedback the paper also suggests some avenues for future work in order to make talking browsers and screen readers compatible.

Abstract
The quality of an interactive system can be measured in terms of its usability. Empirical approaches to usability evaluation attempt to assess the system under real usage conditions. This type of approach can be very expensive. Analytical approaches have been proposed as a means of reasoning about usability issues from early in development. These approaches use models to focus the analysis in specific usuability issues. In this context, the aplication of (mathematically) formal notations and tools has been proposed. This paper presents a formal approach to the analysis of interactive systems. The analysis can be carried out taking into account all possible behaviours of the device, or it can be guided by the tasks the device is supposed to support.

Abstract
Formal reasoning about how users and systems interact poses a difficult challenge. Interactive systems design provides a context in which the subjective area of human understanding meets the objectivity of computer systems logic. We present results of a case study in the use of automated reasoning to aid the formal analysis of interactive systems. We show how we can use human-factors issues to generate properties of interest, and how we can use model checking and theorem proving to analyse our specifications against those properties. This is part of ongoing work in the development of a tool to allow the automatic translation of interactor based specifications into SMV, and in the analysis of the role which different verification techniques might have during the development of interactive systems.

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