University of Hagen at QA@CLEF 2008: Efficient Question Answering with Question Decomposition and Multiple Answer Streams

The German question answering (QA) system IRSAW (formerly: InSicht) participated in QA@CLEF for the fifth time. IRSAW was introduced in 2007, by integrating the deep answer producer InSicht, several shallow answer producers, and a logical validator. InSicht realizes a deep QA approach: it transforms documents to semantic representations using a parser, draws inferences on semantic representations with rules, and matches semantic representations derived from questions and documents. InSicht was improved for QA@CLEF 2008 mainly in the following areas. The coreference resolver was trained on question series instead of newspaper texts in order to be better applicable for follow-up questions in question series. Questions are decomposed by several methods on the level of semantic representations. On the shallow processing side, the number of answer producers was increased from 2 to 4, by adding FACT and SHASE. The answer validator introduced in the previous year was replaced with the faster RAVE validator designed for logic-based answer validation under time constraints. Using RAVE for merging the results of the answer producers, monolingual German runs and bilingual runs with source language English and Spanish were produced by applying a machine translation web service. An error analysis showed the main problems for the precision-oriented deep answer producer InSicht and the potential offered by the recall-oriented shallow answer producers.