In this paper we present a new algorithm for document clustering called Condensed Star (ACONS). This algorithm is a natural evolution of the Star algorithm proposed by Aslam et al., and improved by them and other researchers. In this method, we introduced a new concept of star allowing a different star-shaped form; in this way we retain the strengths of previous algorithms as well as address previous shortcomings. The evaluation experiments on standard document collections show that the proposed algorithm outperforms previously defined methods and obtains a smaller number of clusters. Since the ACONS algorithm is relatively simple to implement and is also efficient, we advocate its use for tasks that require clustering, such as information organization, browsing, topic tracking, and new topic detection.

Abstract. In this paper, a new algorithm for mining frequent connected subgraphs called gRed (graph Candidate Reduction Miner) is presented. This algorithm is based on the gSpan algorithm proposed by Yan and Jan. In this method, the mining process is optimized introducing new heuristics to reduce the number of candidates. The performance of gRed is compared against two of the most popular and efficient algorithms available in the literature (gSpan and Gaston). The experimentation on real world databases shows the performance of our proposal overcoming gSpan, and achieving better performance than Gaston for low minimal support when databases are large.

An automatic linear text segmentation in order to detect the best topic boundaries is a difficult and very useful task in many text processing systems. Some methods have tried to solve this problem with reasonable results, but they present some drawbacks as well. In this work, we propose a new method, called ClustSeg, based on a predefined window and a clustering algorithm to decide the topic cohesion. We compare our proposal against the best known methods, with a better performance against these algorithms.

In this paper a new algorithm, called CStar, for document clustering is presented. This algorithm improves recently developed algorithms like Generalized Star (GStar) and ACONS algorithms, originally proposed for reducing some drawbacks presented in previous Star-like algorithms. The CStar algorithm uses the Condensed Star-shaped Subgraph concept defined by ACONS, but defines a new heuristic that allows to construct a new cover of the thresholded similarity graph and to reduce the drawbacks presented in GStar and ACONS algorithms. The experimentation over standard document collections shows that our proposal outperforms previously defined algorithms and other related algorithms used to document clustering.

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