Multiple viewpoints as an approach to digital library interfaces

We introduce a framework of multiple viewpoint systems for describing and designing systems that use more than one representation or set of relevance judgments on the same collection. A viewpoint is any representational scheme on some collection of data objects together with a mechanism for accessing this content. A multiple viewpoint system allows a searcher to pose queries to one viewpoint and then change to another viewpoint while retaining a sense of context. Multiple viewpoint systems are well suited to alleviate vocabulary mismatches and to take advantage of the possibility of combining evidence. We discuss some of the issues that arise in designing and using such systems and illustrate the concepts with several examples.