Protocols for asymmetric communication channels
Journal of Computer and System Sciences
Information Theory and Reliable Communication
Information Theory and Reliable Communication
Strategies for Hotlink Assignments
ISAAC '00 Proceedings of the 11th International Conference on Algorithms and Computation
Near-entropy hotlink assignments
ESA'06 Proceedings of the 14th conference on Annual European Symposium - Volume 14
Reducing human interactions in Web directory searches
ACM Transactions on Information Systems (TOIS)
On the Complexity of Optimal Hotlink Assignment
ESA '08 Proceedings of the 16th annual European symposium on Algorithms
Approximate Hotlink Assignment
ISAAC '01 Proceedings of the 12th International Symposium on Algorithms and Computation
Adaptive web sites: an AI challenge
IJCAI'97 Proceedings of the 15th international joint conference on Artifical intelligence - Volume 1
Enhancing hyperlink structure for improving web performance
Journal of Web Engineering
WADS'05 Proceedings of the 9th international conference on Algorithms and Data Structures
Efficient algorithms for the hotlink assignment problem: the worst case search
ISAAC'04 Proceedings of the 15th international conference on Algorithms and Computation
Constant factor approximations for the hotlink assignment problem
WADS'07 Proceedings of the 10th international conference on Algorithms and Data Structures
Optimal approximability of bookmark assignments
Discrete Applied Mathematics
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Let G=(V,E) be a graph representing a Web site, where nodes correspond to pages and arcs to hyperlinks. In this context, hotlinks are defined as shortcuts (new arcs) added to Web pages of G in order to reduce the time spent by users to reach their desired information. In this article, we consider the problem where G is a rooted directed tree and the goal is minimizing the expected time spent by users by assigning at most k hotlinks to each node. For the most studied version of this problem where at most one hotlink can be added to each node, we prove the existence of two FPTAS's which optimize different objectives considered in the literature: one minimizes the expected user path length and the other maximizes the expected reduction in user path lengths. These results improve over a constant factor approximation for the expected length and over a PTAS for the expected reduction, both obtained recently in Jacobs [2007]. Indeed, these FPTAS's are essentially the best possible results one can achieve under the assumption that P &neq; NP. Another contribution we give here is a 16-approximation algorithm for the most general version of the problem where up to k hotlinks can be assigned from each node. This algorithm runs in O(|V| log |V|) time and it turns to be the first algorithm with constant approximation for this problem.