Towards the Notion of Typical Documents in Large Collections of Documents

This chapter presents a new measure of document similarity – the GNGrank that was inspired by the popular opinion that links between the documents reflect similar content. The idea was to create a rank measure based on the well known PageRank algorithm which exploits the document similarity to insert links between the documents. A comparative study of various link- and content-based similarity measures, and GNGrank is performed in the context of identification of a typical document of a collection. The study suggests that each group of them measures something different, a different aspect of document space, and hence the respective degrees of typicality do not correlate. This may be an indication that for different purposes different documents may be important. A deeper study of this phenomenon is our future research goal.