Discusses two query evaluation strategies used in large text retrieval systems: (1) term-at-a-time; and (2) document-at-a-time. Describes optimization techniques that can reduce query evaluation costs. Presents simulation results that compare the performance of these optimization techniques when applied to natural language query evaluation. (JMV)

Describes an information retrieval system in which advanced natural language processing is used to enhance the effectiveness of term-based document retrieval by preprocessing the documents; discovering interterm dependencies and build a conceptual hierarchy specific to database domain; and processing the user's natural language requests into…

Describes and evaluates a system that selects key information from an event database by reasoning about event frequencies, frequencies of relations between events, and domain-specific importance measures. The system aggregates similar information and plans a summary tailored to a stereotypical user. (AEF)

Increasing information retrieval performance using phrases and part-of-speech (POS) information is one example of a type of decision-making performance that is improved when using this linguistic information. The relative effectiveness of using multi-term phrases as opposed to individual terms is shown, as well as the relative worth of POS tagged…