Hyperlink Exploration

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This approach analyzes hyperlinks to uncover two types of pages:

• Authorities: provide the best source of information on a given topic.
• Hubs: provide collections of links to authorities.

Finding Authorities and Hubs
This algorithm uses two major steps:

1. A sampling component, which constructs a focused collection of several thousand pages likely to be rich in relevant authorities; and


2. A weight-propagation component, which determines numerical estimates of hub and authority weights by an iterative procedure.
   
   

   Authority weight update: If a page is pointed to by many good hubs, we would like to increase its authority weight xp, for a page p, by the sum of yq over all pages q that link to p.

   
   

   Hub weight update: In a strictly dual fashion, if a page points to many good authorities, we increase its hub weight.

   
   The notation q→p indicates that q links to p.

Implementation
Collect the t highest-ranked pages for the query q from a search engine. A root set and a base set

are relatively small, and are rich in relevant pages. Additionally, a base set contains most of the strongest authorities.