How does the PageRank algorithm handle links?

Question

We discussed Google's PageRank algorithm in my algorithms class. What we discussed was that the algorithm represents webpages as a graph and puts them in an adjacency matrix, then does some matrix tweaking.

The only thing is that in the algorithm we discussed, if I link to a webpage, that webpage is also considered to link back to me. This seems to make the matrix multiplication simpler. Is this still the way that PageRank works? If so, why doesn't everyone just link to slashdot.com, yahoo.com, and microsoft.com just to boost their page rankings?

Answer 1

If you read the PageRank paper, you will see that links are not bi-directional, at least for the purposes of the PageRank algorithm. Indeed, it would make no sense if you could boost your page's PageRank by linking to a highly valued site.

Answer 2

If you link to the web page, that web page gets it's pagerank number increased according to your site page rank.

It doesn't work the other way around. Links are not bidirectional. So if you link to slashdot, you won't get any increase in pagerank, if slashdot links to you, you will get increase in pagerank.

Answer 3

Its a mystery beyond what we know about the beginnings of backrub and the paper that avi linked.

My favorite (personal) theory involves lots and lots of hamsters with wheel revolutions per minute heavily influencing the rank of any particular page. I don't know what they give the hamsters .. probably something much milder than LSD.

Answer 4

See the paper "The 25 Billion dollar eigenvector" http://www.rose-hulman.edu/~bryan/googleFinalVersionFixed.pdf