Browsing by Subject "Pruning techniques"

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Open Access
Exploiting index pruning methods for clustering XML collections
(Springer, Berlin, Heidelberg, 2010) Altıngövde, İsmail Şengör; Atılgan, Duygu; Ulusoy, Özgür
In this paper, we first employ the well known Cover-Coefficient Based Clustering Methodology (C3M) for clustering XML documents. Next, we apply index pruning techniques from the literature to reduce the size of the document vectors. Our experiments show that for certain cases, it is possible to prune up to 70% of the collection (or, more specifically, underlying document vectors) and still generate a clustering structure that yields the same quality with that of the original collection, in terms of a set of evaluation metrics. © 2010 Springer-Verlag Berlin Heidelberg.
Open Access
Static index pruning in web search engines: combining term and document popularities with query views
(Association for Computing Machinery, 2012) Altingovde, I. S.; Ozcan, R.; Ulusoy, O.
Static index pruning techniques permanently remove a presumably redundant part of an inverted file, to reduce the file size and query processing time. These techniques differ in deciding which parts of an index can be removed safely; that is, without changing the top-ranked query results. As defined in the literature, the query view of a document is the set of query terms that access to this particular document, that is, retrieves this document among its top results. In this paper, we first propose using query views to improve the quality of the top results compared against the original results. We incorporate query views in a number of static pruning strategies, namely term-centric, document-centric, term popularity based and document access popularity based approaches, and show that the new strategies considerably outperform their counterparts especially for the higher levels of pruning and for both disjunctive and conjunctive query processing. Additionally,we combine the notions of term and document access popularity to form new pruning strategies, and further extend these strategies with the query views. The new strategies improve the result quality especially for the conjunctive query processing, which is the default and most common search mode of a search engine. © 2012 ACM.
Open Access
XML retrieval using pruned element-index files
(Springer, Berlin, Heidelberg, 2010) Altıngövde, İsmail Şengör; Atılgan, Duygu; Ulusoy, Özgür
An element-index is a crucial mechanism for supporting content-only (CO) queries over XML collections. A full element-index that indexes each element along with the content of its descendants involves a high redundancy and reduces query processing efficiency. A direct index, on the other hand, only indexes the content that is directly under each element and disregards the descendants. This results in a smaller index, but possibly in return to some reduction in system effectiveness. In this paper, we propose using static index pruning techniques for obtaining more compact index files that can still result in comparable retrieval performance to that of a full index. We also compare the retrieval performance of these pruning based approaches to some other strategies that make use of a direct element-index. Our experiments conducted along with the lines of INEX evaluation framework reveal that pruned index files yield comparable to or even better retrieval performance than the full index and direct index, for several tasks in the ad hoc track. © 2010 Springer-Verlag Berlin Heidelberg.