Now showing items 1-13 of 13

    • An automatic approach to construct domain-specific web portals 

      Altıngövde, İsmail Şengör; Özcan, Rıfat; Çetintaş, Süleyman; Yılmaz, Hakan; Ulusoy, Özgür (ACM, 2007-11)
      We describe the architecture of an automatic domain-specific Web portal construction system. The system has three major components: i) a focused crawler that collects the domain-specific pages on the Web, ii) an information ...
    • Caching techniques for large scale web search engines 

      Özcan, Rıfat (Bilkent University, 2011)
      Large scale search engines have to cope with increasing volume of web content and increasing number of query requests each day. Caching of query results is one of the crucial methods that can increase the throughput of ...
    • Characterizing web search queries that match very few or no results 

      Altıngövde, İ. Ş.; Blanco, R.; Cambazoğlu, B. B.; Özcan, Rıfat; Sarıgil, Erdem; Ulusoy, Özgür (ACM, 2012-11)
      Despite the continuous efforts to improve the web search quality, a non-negligible fraction of user queries end up with very few or even no matching results in leading web search engines. In this work, we provide a detailed ...
    • Evolution of web search results within years 

      Altıngövde, İsmail Şengör; Özcan, Rıfat; Ulusoy, Özgür (ACM, 2011-07)
      We provide a first large-scale analysis of the evolution of query results obtained from a real search engine at two distant points in time, namely, in 2007 and 2010, for a set of 630,000 real queries.
    • Exploiting query views for static index pruning in web search engines 

      Altıngövde, İsmail Şengör; Özcan, Rıfat; Ulusoy, Özgür (ACM, 2009-11)
      We propose incorporating query views in a number of static pruning strategies, namely term-centric, document-centric and access-based approaches. These query-view based strategies considerably outperform their counterparts ...
    • In praise of laziness: A lazy strategy for web information extraction 

      Özcan, Rıfat; Altıngövde, I. Ş.; Ulusoy, Özgür (2012)
      A large number of Web information extraction algorithms are based on machine learning techniques. For such extraction algorithms, we propose employing a lazy learning strategy to build a specialized model for each test ...
    • Large-scale cluster-based retrieval experiments on Turkish texts 

      Altıngövde, İsmail Şengör; Özcan, Rıfat; Öcalan Hüseyin C.; Can, Fazlı; Ulusoy, Özgür (ACM, 2007)
      We present cluster-based retrieval (CBR) experiments on the largest available Turkish document collection. Our experiments evaluate retrieval effectiveness and efficiency on both an automatically generated clustering ...
    • A practitioner's guide for static index pruning 

      Altıngövde, İsmail Şengör; Özcan, Rıfat; Ulusoy, Özgür (Springer, 2009-04)
      We compare the term- and document-centric static index pruning approaches as described in the literature and investigate their sensitivity to the scoring functions employed during the pruning and actual retrieval stages. ...
    • Space efficient caching of query results in search engines 

      Özcan, Rıfat; Altıngövde, İsmail Şengör; Ulusoy Özgür (IEEE, 2008-10)
      Web search engines serve millions of query requests per day. Caching query results is one of the most crucial mechanisms to cope with such a demanding load. In this paper, we propose an efficient storage model to cache ...
    • Static query result caching revisited 

      Özcan, Rıfat; Altıngövde, İsmail Şengör; Ulusoy, Özgür (ACM, 2008-04)
      Query result caching is an important mechanism for search engine efficiency. In this study, we first review several query features that are used to determine the contents of a static result cache. Next, we introduce a new ...
    • Timestamp-based cache invalidation for search engines 

      Alıcı, Sadiye; Altıngövde, İsmail Şengör; Özcan, Rıfat; Cambazoglu, B.B.; Ulusoy, Özgür (ACM, 2011)
      We propose a new mechanism to predict stale queries in the result cache of a search engine. The novelty of our approach is in the use of timestamps in staleness predictions. We show that our approach incurs very little ...
    • Timestamp-based result cache invalidation for web search engines 

      Alıcı, Sadiye; Altingovde I.S.; Özcan, Rıfat; Cambazoglu, B.B.; Ulusoy, Özgür (ACM, 2011)
      The result cache is a vital component for efficiency of large-scale web search engines, and maintaining the freshness of cached query results is the current research challenge. As a remedy to this problem, our work proposes ...
    • Utilization of navigational queries for result presentation and caching in search engines 

      Özcan, Rıfat; Altıngövde, İsmail Şengör; Ulusoy, Özgür (ACM, 2008-10)
      We propose result page models with varying granularities for navigational queries and show that this approach provides a better utilization of cache space and reduces bandwidth requirements.