Information retrieval and digital libraries: lessons of research

This paper reviews lessons from the history of information retrieval research, with particular emphasis on recent developments. These have demonstrated the value of statistical techniques for retrieval, and have also shown that they have an important, though not exclusive, part to play in other information processing tasks, like question asnwering and summarising. The heterogeneous materials that digital libraries are expected to cover, their scale, and their changing composition, imply that statistical methods, which are general-purpose and very flexible, have significant potential value for the digital libraries of the future.