Query Processing for Retrieval from Large Text Bases

Natural language experiments in information retrieval have often been inconclusive due to the lack of large text bases with associated queries and relevance judgments. This paper describes experiments in incremental query processing and indexing with the INQUERY information retrieval system on the TIPSTER queries and document collection. The results measure the value of processing tailored for different query styles, use of syntactic tags to produce search phrases, recognition and application of generic concepts, and automatic concept extraction based on interword associations in a large t e x t base . 1. I N T R O D U C T I O N : T I P S T E R A N D INQUERY Previous research has suggested that retrieval effectiveness might be enhanced by the use of multiple representations and by au tomated language processing techniques. Techniques include automat ic or interactive introduction of synonyms [Har88], forms-based interfaces [CD90], automatic recognition of phrases [CTLgl], and relevance feedback [SB90]. The recent development of the T I P S T E R corpus with associated queries and relevance judgments has provided new opportunities for judging the effectiveness of these techniques on large heterogenous document collections. 1.1. T I P S T E R Text Base and Query Topics The T I P S T E R documents comprise two volumes of text, of approximately one gigabyte each, from sources such as newspaper and magazine articles and government publications (Federal Register). Accompanying the collections are two sets of fifty topics. Each topic is a full text description, in a specific format, of an information need. (Figure 1). Each T I P S T E R topic offers several representations of the same information need. The Topic and Description fields are similar to what might be entered as a query in a traditional information retrieval system. The Narrative field expands on the information need, giving an overview of the classes of documents which would or < t o p > < d o m > Domain: International Economics Topic: Satellite Launch Contracts Description: Document will cite the signing of a contract or preliminary agreement, or the making of a tentative reservation, to launch a commercial satellite. < n a r r > Narrative: A relevant document will mention the signing of a contract or preliminary agreement, or the making of a tentative reservation, to launch a commerciM satellite. Concept(s): 1. contract, agreement 2. launch vehicle, rocket, payload, satellite 3. launch services, commercial space industry, commercial launch industry 4. Arianespace, Martin Marietta, General Dynamics, McDonnell Douglas 5. Titan, Delta II, Atlas, Ariane, Proton