Every document has a geographical scope

摘要

It is a useful premise to assume that every document in a collection and every query issued to an information retrieval (IR) system are geography-dependent. If one can determine what area an article is about (i.e., its geographical scope), this information can be used to improve the accuracy with which people, places and organisations named in the article can be located. More importantly, geographical scopes of documents may be exploited to improve the performance of IR systems against geography-dependent user queries by tuning relevance ranking and query expansion strategies with scope metadata. We want to answer the following pertinent questions to ascertain the usefulness of geographical information in improving retrieval accuracy: (1) how far can geographical information in queries and documents improve retrieval accuracy of IR systems when answering geography-dependent queries; and, (2) how effectively can geographical information in queries and documents be utilised to improve the quality of relevance ranking in geographical IR domain. This paper outlines strategies to determine the geographical scope of documents, and describes methods to utilise scope information to improve the performance of toponym resolution, relevance ranking and query expansion.