AQUA: A Knowledge-Based Architecture for a Question Answering System

This paper describes AQUA, a question answering system. AQUA combines Natural Language processing (NLP), Ontologies, Logic, and Information Retrieval technologies in a uniform framework. AQUA makes intensive use of an ontology (which encodes knowledge) in several parts of the question answering system. The ontology is used in the refinement of the initial query, the reasoning process (a generalization/specialization process using classes and subclasses from the ontology), and in the novel similarity algorithm. The similarity algorithm is a key feature of AQUA. It is used to find similarities between relations/concepts in the translated query and relations/concepts in the ontological structures. The similarities detected then allow the interchange of concepts or relations in a logic formula corresponding to the user query. In this way, we make the mapping between user's queries and ontological spaces. The AQUA architecture is flexible enough to allow that AQUA can be used as closed-domain and open domain question answering system.