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Using multiple ontologies in information extraction

Ontology-Based Information Extraction (OBIE) has recently emerged as a subfield of Information Extraction (IE). Here, ontologies - which provide formal and explicit specifications of conceptualizations - play a crucial role in the information extraction process. Several OBIE systems have been implemented previously but all of them use a single ontology although multiple ontologies have been designed for many domains. We have studied the theoretical basis for using multiple ontologies in information extraction and have developed information extraction systems that use them. These systems investigate the two major scenarios for having multiple ontologies for the same domain: specializing in sub-domains and providing different perspectives. The domain of universities has been used for the former scenario through a corpus collected from university websites. For the latter, the domain of terrorist attacks and a corpus used by a previous Message Understanding Conference (MUC) have been used. The results from these two case studies indicate that using multiple ontologies in information extraction has led to a clear improvement in performance measures.