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European Symposium on Algorithms

ESA 2008: Algorithms - ESA 2008 pp 540–552Cite as

On the Complexity of Optimal Hotlink Assignment

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Part of the book series: Lecture Notes in Computer Science ((LNTCS,volume 5193))

Abstract

The concept of hotlink assignment aims at reducing the navigation effort for users of a web directory or similar structure by inserting a limited number of additional hyperlinks called hotlinks. Given an access probability distribution of the leaves of the tree representing the web site, the goal of hotlink assignment algorithms is to minimize the expected path length between the root and the leaves.

We prove that this optimization problem is NP-hard, even if only one outgoing hotlink is allowed for each node. This answers a question that has been open since the first formulation of the problem in [3].

In this work we also investigate the model where hotlinks are only allowed to point at the leaves of the tree. We demonstrate that for this model optimal solutions can be computed in polynomial time. Our algorithm operates in a very general setting, where the maximum number of outgoing hotlinks is specified individually for each node. Experimental evaluation shows that the algorithm is applicable in practice.

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Authors and Affiliations

  1. Department of Computer Science, University of Freiburg,  

    Tobias Jacobs

Authors
  1. Tobias Jacobs
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Dan Halperin Kurt Mehlhorn

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© 2008 Springer-Verlag Berlin Heidelberg

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Jacobs, T. (2008). On the Complexity of Optimal Hotlink Assignment. In: Halperin, D., Mehlhorn, K. (eds) Algorithms - ESA 2008. ESA 2008. Lecture Notes in Computer Science, vol 5193. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-87744-8_45

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  • DOI: https://doi.org/10.1007/978-3-540-87744-8_45

  • Publisher Name: Springer, Berlin, Heidelberg

  • Print ISBN: 978-3-540-87743-1

  • Online ISBN: 978-3-540-87744-8

  • eBook Packages: Computer ScienceComputer Science (R0)

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