  It might appear that natural language processing should improve the accuracy
of information retrieval systems, by making available a more detailed analysis
of queries and documents. Although past results appear to show that this is not
so, if the focus is shifted to short phrases rather than full documents, the
situation becomes somewhat different. The ANVIL system uses a natural language
technique to obtain high accuracy retrieval of images which have been annotated
with a descriptive textual caption. The natural language techniques also allow
additional contextual information to be derived from the relation between the
query and the caption, which can help users to understand the overall
collection of retrieval results. The techniques have been successfully used in
a information retrieval system which forms both a testbed for research and the
basis of a commercial system.
