HITS score

From Wikipedia, the free encyclopedia

Hyperlink-Induced Topic Search (HITS; also known as hubs and authorities) is a link analysis algorithm that rates Web pages, developed by Jon Kleinberg. The idea behind Hubs and Authorities stemmed from a particular insight into the creation of web pages when the Internet was originally forming; that is, certain web pages, known as hubs, served as large directories that were not actually authoritative in the information that they held, but were used as compilations of a broad catalog of information that led users direct to other authoritative pages. In other words, a good hub represents a page that pointed to many other pages, while a good authority represents a page that is linked by many different hubs.1

It has not been developped directly for the structure of Wikipedia nor does it take into account where the link is placed. Wikipedia would be just a graph

Pseudo code:

Here is te pseucode of the HITS algorithm

G := set of pages
for each page p in G do
    p.auth = 1 // p.auth is the authority score of the page p
    p.hub = 1 // p.hub is the hub score of the page p
for step from 1 to k do // run the algorithm for k steps
    norm = 0
    for each page p in G do  // update all authority values first
        p.auth = 0
        for each page q in p.incomingNeighbors do // p.incomingNeighbors is the set of pages that link to p
            p.auth += q.hub
        norm += square(p.auth) // calculate the sum of the squared auth values to normalise
    norm = sqrt(norm)
    for each page p in G do  // update the auth scores 
        p.auth = p.auth / norm  // normalise the auth values
    norm = 0
    for each page p in G do  // then update all hub values
        p.hub = 0
        for each page r in p.outgoingNeighbors do // p.outgoingNeighbors is the set of pages that p links to
            p.hub += r.auth
        norm += square(p.hub) // calculate the sum of the squared hub values to normalise
    norm = sqrt(norm)
    for each page p in G do  // then update all hub values
        p.hub = p.hub / norm   // normalise the hub values

more details can be found here

Pagerank

Careful even if the HITS score has similar properties with PageRank, they are not the same.

Licence note:

Attribution: This page includes material adapted from the Wikipedia article “HITS algorithm” (see page history), used under the CC BY-SA 4.0 license. Changes: formatting and edits; added pseudocode and extra notes.