lecture17-linkanalysis-handout-6-per

19 introducon to informaon retrieval s ec 212

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Unformatted text preview: d   Once search engines began to use links for ranking (roughly 1998), link spam grew   You can join a group of websites that heavily link to one another 18 3 Introduc)on to Informa)on Retrieval Introduc)on to Informa)on Retrieval In ­links to pages – unusual pa\erns  S ec. 21.2 Pagerank scoring   Imagine a browser doing a random walk on web pages: 1/3 1/3   Start at a random page 1/3   At each step, go out of the current page along one of the links on that page, equiprobably   In the steady state each page has a long ­term visit rate  ­ use this as the page s score. 19 Introduc)on to Informa)on Retrieval S ec. 21.2 Introduc)on to Informa)on Retrieval Sec. 21.2 Not quite enough Telepor*ng   The web is full of dead ­ends.   At a dead end, jump to a random web page.   At any non ­dead end, with probability 10%, jump to a random web page.  ...
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This document was uploaded on 02/26/2014.

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