12. The computer-readable storage medium of claim 11 wherein the identifying of author clusters includes: generating a publication vector for each author, a publication vector identifying papers authored by the author; and clustering the authors based on distance between the publication vectors.
11. A computer-readable storage medium containing instructions for controlling a computer system to provide information about authors that have a relationship, by a method comprising: accessing indications of authors of papers to identify clusters of authors based on co-author relationships between the authors wherein authors within a same cluster have a co-author relationship; storing an indication of the identified clusters of authors; and calculating an importance of authors within an author cluster wherein the importance of an author is defined recursively based on the importance of the papers authored by the author and wherein the importance of an author and a paper is defined as follows: 
 R author =W diag( R paper N T paper ) 
 R paper =W T diag( R author N T author ) where R author is a vector of the importance of the authors, R paper is a vector of the importance of the papers, W is an adjacency matrix mapping authors to papers, W T is a transpose of the adjacency matrix W, N T paper is a matrix of normalization terms for the papers, and N T author is a matrix of normalization terms for the authors.