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4.74 Degrees of Separation on Facebook

vigna Well, as one of the authors... (216 comments)

...I made three days ago a submission with the correct number (3.74). /. couldn't care less. On average the degrees are 3.74, and this is why our paper is called "Four degrees of separation". 4.74 is the distance, which is one more than the degrees of separation. Unfortunately sociologists decided to count the "intermediaries" (so if we are friends, our degree of separation is zero), whereas computer scientists count "hops" (so if we are friends, our distance is one). This generated a lot of confusion. But, just to be clear, no, we did not round 4.74 down to 4; we rounded 3.74 up to 4. :)

more than 3 years ago

ERD Apps a Missing OSS Niche?

vigna ERW (25 comments)

Maybe you could find useful the stuff we developed for our internal usage: http://erw.dsi.unimi.it .

There is presently no graphical tool for editing diagrams--you must describe your schema using XML (we are working on graphical tool, but it is still, at best, immature).

more than 12 years ago



The first open ranking of the World Wide Web is out!

vigna vigna writes  |  about a year ago

vigna (590069) writes "The Laboratory for Web Algorithmics together with the Data and Web Science Group of the University of Mannheim have put together the first entirely open ranking of more than 100 million sites of the World Wide Web. The ranking is based on classic and easily explainable centrality measures applied to a host graph, and it is entirely open—all data and all software used is publicly available. Just in case you wonder, the first site is YouTube, the second one Wikipedia and the third one Twitter."
Link to Original Source

Google is sending out blankets [sic] to open-source developers

vigna vigna writes  |  about a year and a half ago

vigna (590069) writes "A few weeks ago I received an email from Google’s Open Source Programs Office. My work on open-source libraries (fastutil? MG4J? Sux4J? who knows) had been recognised. So I got $175 to spend on the Google store (wow, that's generous!) and I had to give my address to receive a "special thank you gift". After a couple of weeks, a large FedEx package arrived. It contained a *blanket*.

Yes, you read it right the first time. Google is sending out polyester blankets as a special gift to open-source developers.

To me, that's a bit weird."

Four Degrees of Separation

vigna vigna writes  |  more than 3 years ago

vigna writes "Facebook has just released two studies (I've been involved in one of them) about the structure of the Facebook graph. Using HyperANF, an algorithm for estimating the distance distribution of very large graphs developed at the Laboratory of Web Algorithmics, we have been able to estimate accurately the average degree of separation on Facebook... and it's just 3.74 (one less than the average distances, which is 4.74). So the play "Six degrees of separation" was a little bit pessimistic. The degree distribution of Facebook has been unveiled, too.

The story has been picked up by the New York Times, but alas, they mistook the average distance for the degrees of separation."

Link to Original Source

PageRank has been rediscovered for 50 years

vigna vigna writes  |  more than 4 years ago

vigna (590069) writes "A recent post on Slashdot argued that PageRank, the algorithm original developed by Sergey Brin and Larry Page in 1998 to rank web pages in Google, has a precursor in Leontief's input-output economic theory (1941). The link, however, is very weak, as Leontief is just interested in a pricing that makes an economy stable. Much more surprising is that Seeley in 1949 proposed to rank children popularity recursively, using their reciprocal "I-like" relationships, exactly as PageRank does. Wei in 1952 proposed to rank sport teams in the same way using the score of matches as "I'm-better-then" relationships, and Katz defined in 1953 its famous social index, which is exactly PageRank modulo a matrix normalization. The mathematics of all these contributions has been unified in a recent paper that tries to show how spectral ranking has been rediscovered over, over, and over for more than 50 years."


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