The web has become a major tool for communication, services and an outstanding source of knowledge. It has also grown in com plexity, and end-users may experience difficulties in reading and acquiring good understanding of some overly complex or poorly designed web pages. This observation is even more valid for people with visual disabilities. In this paper, we focus on people with low or weakening vision, for whom we propose to adapt web pages to their needs, while preserving the spirit of the original design. In this context, obtaining a web page adaptation in a very short time may be a difficult problem, because user and designer needs and prefer ences may contradict each other, and because there may be a large number of adaptation possibilities. Finding a relevant adaptation in a large search space can hardly be done by an algorithm which com putes and assesses all possible solutions, which brings us to con sider evolutionary algorithms. A characteristic of our problem is to consider a set of preferences, each being implemented by an evalu ation function. This optimization problem can be dealt with multiobjective genetic algorithms, including the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and its next version (NSGA-III). NSGA-III has been recently introduced to address many-objective optimization problems (having more that four objectives). We com pare NSGA-II and NSGA-III performances in the context of adapt ing web pages in accordance to a set of preferences. The compar ison is based on running time, number of generations and quality of computed adaptation (number of satisfied objectives). We also show the importance of several parameters including population size, crossover/mutation probability, and the opportunity to aggre gate objective functions. From the obtained results, we conclude that the approach is feasible and effective on realistic web pages, especially with NSGA-III.

Digital technologies are an opportunity to overcome disabilities, provided that accessibility is ensured. In this paper, we focus on visual accessibility and the way it is supported in Operating Systems (OS). The significant variability in this support has practical consequences, e.g., the difficulty to recommend or select an OS, or migrate from one OS to another. This suggests building a variability model for OS that would classify them and would serve as a reference. We propose a methodology to build such a variability model with the help of the Formal Concept Analysis (FCA) framework. In addition, as visual accessibility can be divided into several concerns (e.g., zoom, or contrast), we leverage an extension of FCA, namely Relational Concept Analysis. We also build an ontology to dispose of a standardized description of visual accessibility options. We apply our proposal to the analysis of the variability of a few representative operating systems.