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<Paper uid="H05-1118">
  <Title>Proceedings of Human Language Technology Conference and Conference on Empirical Methods in Natural Language Processing (HLT/EMNLP), pages 939-946, Vancouver, October 2005. c(c)2005 Association for Computational Linguistics Integrating linguistic knowledge in passage retrieval for question answering</Title>
  <Section position="1" start_page="0" end_page="0" type="abstr">
    <SectionTitle>
Abstract
</SectionTitle>
    <Paragraph position="0"> In this paper we investigate the use of linguistic knowledge in passage retrieval as part of an open-domain question answering system. We use annotation produced by a deep syntactic dependency parser for Dutch, Alpino, to extract various kinds of linguistic features and syntactic units to be included in a multi-layer index. Similar annotation is produced for natural language questions to be answered by the system. From this we extract query terms to be sent to the enriched retrieval index.</Paragraph>
    <Paragraph position="1"> We use a genetic algorithm to optimize the selection of features and syntactic units to be included in a query. This algorithm is also used to optimize further parameters such as keyword weights. The system is trained on questions from the competition on Dutch question answering within the Cross-Language Evaluation Forum (CLEF). We could show an improvement of about 15% in mean total reciprocal rank compared to traditional information retrieval using plain text keywords (including stemming and stop word removal). null</Paragraph>
  </Section>
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