> retrieving the top k results (e.g. using a vector space ranking
> method), and then retrieving links that the results forward points to
> (authorities) and also the links that are backwardly linking to it
> (hubs). In its entirety, this graph of links is called the "base
> set". Additional value can be extracted by also considering the other
> links (new authorities) that the hubs point to, and the other links
> (new hubs) that point to the authorities.