document: Mirror site maintenance based on evolution associations of web directories Mirroring Web sites is a well-known technique commonly used in the Web community . A mirror site should be updated frequently to ensure that it reflects the content of the original site . Existing mirroring tools apply page-level strategies to check each page of a site , which is inefficient and expensive . In this paper , we propose a novel site-level mirror maintenance strategy . Our approach studies the evolution of Web directorystructures and mines association rules between ancestor-descendant Web directories . Discovered rules indicate the evolution correlations between Web directories . Thus , when maintaining the mirror of a Web site ( directory ) , we can optimally skipsubdirectories which are negatively correlated with it in undergoing significant changes . The preliminary experimental results show that our approach improves the efficiency of the mirror maintenance process significantly while sacrificing slightly in keeping the `` freshness '' of the mirrors .
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