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Modélisation et optimisation de problèmes de synchronisation dans les documents hypermédia

Abstract : The actual formats used to publish documents on the Internet bring, without discussion, new facilities compared to the paper material. But needs are still growing and new languages appear regularly, attempting to improve the structure and the interactivity of documents. Among these languages, some offer the possibility of animating and synchronizing media components. But the variety of these components (audio, video, text, image...) makes the animation a difficult problem. The author of a synchronized document provides a set of temporal constraints on the components to describe the progress of the presentation. Each of these components has a duration of presentation that is flexible within some boundaries. The problem consists in finding a good adjustment of the durations so the presentation progresses as close as possible to what the author wants with avoiding any pause.

The problem can be modeled, after some restrictions, as a minimal cost tension problem in a graph. To solve it with piecewise convex costs, we studied different methods (linear programming, out-of-kilter, cost-scaling on the dual). We also propose an adaptation of the out-of-kilter for convex differentiable costs. All these methods are compared on theoretical and practical aspects, considering graphs without any peculiar structure.

The graphs representing the temporal constraints are in fact very structured and very close to the class of graphs called series-parallel, and the methods designed for any graph appear to be sometimes inefficient. We propose a polynomial method, with O(m3) operations, more adapted to solve the problem on series-parallel graphs, and that we call aggregation. But these graphs, although very close to the real cases, are still an idealization. We propose to measure the series-parallel aspect of a graph by defining the notion of almost series-parallel graph, based on the decomposition of the graph into series-parallel components. By using the efficiency of the aggregation method on this decomposition, we propose a method called reconstruction that allows to solve the problem for almost series-parallel graphs more efficiently than the methods studied previously.

During this study, we developed a library of reusable components for graph problems. We explain why this kind of development can not always follow the classical rules of software engineering. We show how the object paradigm can nevertheless be used to create efficient tools for operations research. And we propose design patterns to work software components (algorithms and data structures) out that are generic, meaning independent of the data structures they manipulate and of the algorithms they use, still being highly extensible, and all this with a minimal loss of efficiency.
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https://tel.archives-ouvertes.fr/tel-00002566
Contributor : Bruno Bachelet <>
Submitted on : Wednesday, August 13, 2003 - 2:26:37 PM
Last modification on : Wednesday, February 24, 2021 - 4:24:01 PM
Long-term archiving on: : Monday, October 22, 2012 - 10:55:08 AM

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Bruno Bachelet. Modélisation et optimisation de problèmes de synchronisation dans les documents hypermédia. Recherche opérationnelle [cs.RO]. Université Blaise Pascal - Clermont-Ferrand II, 2003. Français. ⟨tel-00002566v2⟩

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