2009 | OriginalPaper | Buchkapitel
Assessing the Impact of Thesaurus-Based Expansion Techniques in QA-Centric IR
verfasst von : Luís Sarmento, Jorge Teixeira, Eugénio Oliveira
Erschienen in: Evaluating Systems for Multilingual and Multimodal Information Access
Verlag: Springer Berlin Heidelberg
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We study the impact of using thesaurus-based query expansion methods at the Information Retrieval (IR) stage of a Question Answering (QA) system. We focus on expanding queries for questions regarding
actions
and
events
, where verbs have a central role. Two different thesaurus are used: the OpenOffice thesaurus and an automatically generated verb thesaurus. The performance of thesaurus-based methods is compared against what is obtained by (i) executing
no expansion
and (ii) applying a simple query generalization method. Results show that thesaurus-based approaches help improving
recall
at retrieval, while keeping satisfactory
precision
. However, we confirm that positive impact for the final QA performance is mostly achieved due to increase in
recall
, which can also be obtained by using simpler methods. Nevertheless, because of its better relative precision thesaurus-based expansion is effective in selectively reducing the number of
irrelevant
text passages retrieved, thus reducing computational load in the answer extraction stage.