The TALP-QA system for Spanish at CLEF 2004: Structural and hierarchical relaxing of semantic constraints

This paper describes TALP-QA, a multilingual open-domain Question Answering (QA) system that processes both factoid and definition questions. The system is described and evaluated in the context of our participation in the CLEF 2004 Spanish Monolingual QA task. Our approach to factoid questions is to build a semantic representation of the questions and the sentences in the passages retrieved for each question. A set of Semantic Constraints (SC) are extracted for each question. An answer extraction algorithm extracts and ranks sentences that satisfy the SCs of the question. If matches are not possible the algorithm relaxes the SCs structurally (removing constraints) and/or hierarchically (abstracting the constraints using a taxonomy). Answers to definition questions are generated by selecting the text fragment with more density of those terms more frequently related to the question's target (the Named Entity (NE) that appears in the question) throughout the corpus.