This title has been withdrawn from sale on Cambridge Books Online. Institutions who purchased this title previous to removal will continue to have access via Cambridge Books Online but this title can no longer be purchased.
Christopher D. Manning
Publisher: Cambridge University Press
Print Publication Year: 2008
Online Publication Date:June 2012
Chapter DOI: http://dx.doi.org/10.1017/CBO9780511809071.007
Thus far, we have dealt with indexes that support Boolean queries: A document either matches or does not match a query. In the case of large document collections, the resulting number of matching documents can far exceed the number a human user could possibly sift through. Accordingly, it is essential for a search engine to rank-order the documents matching a query. To do this, the search engine computes, for each matching document, a score with respect to the query at hand. In this chapter, we initiate the study of assigning a score to a (query, document) pair. This chapter consists of three main ideas.
Section 6.4 develops several variants of term-weighting for the vector space model. Chapter 7 develops computational aspects of vector space scoring and related topics.