Authoritative sources in a hyperlinked environment

Kleinberg talks about how to extract "authorities" and "hubs" from a bunch of interlinked web pages. Consider, for example, the set of web pages returned by a search engine for a particular query. We're interested in finding the one original and authoritative source for our search term. Google's PageRank is quite good at doing precisely this job (and, perhaps, PigeonRank (http://www.google.com/technology/pigeonrank.html) is even better?). Search for "apple computer" and you'd expect to get www.apple.com back as the first hit, rather than some other page containing the words apple computer. In Kleinberg's teminology, we're seeking an authoritative page.

The dual problem (dual means "reverse all the links between the pages" and then look for the authorities in this upside-down world) is to find a set of hubs. These are not exactly the hubs that Bararbási talks about, but rather the Yahoos and the endless lists of "my favourite links" on personal home pages. The symmetry is that hubs link to lots of pages (including authorities), whereas authorities are liked from a lot of pages (including hubs).

We'll probably see something similar on CiteULike. The hubs will be the real citation classics that everyone's reading in a particular field. The hubs should hopefully be the people who read widely and in different fields and can produce a good overview of how to "glue" a couple of related subjects together. Both are probably worth mining from our dataset.