Popularity versus similarity: a balance that predicts network growth

Do you know who Michael Jackson or George Washington was? You most likely do: they are what we call ''household names'' because these individuals were so ubiquitous. But what about Giuseppe Tartini or John Bachar?

That's much less likely, unless you are a fan of Italian baroque music or free solo climbing.

In that case, you would have heard of Bachar just as likely as Washington. The latter was popular, while the former was not as popular but had interests similar to yours.

A new paper published this week in the science journal Nature by the Cooperative Association for Internet Data Analysis (CAIDA), based at the San Diego Supercomputer Center (SDSC) at the University of California, San Diego, explores the concept of popularity versus similarity, and if one more than the other fuels the growth of a variety of networks, whether it is the internet, a social network of trust between people, or a biological network.

The researchers, in a study called Popularity Versus Similarity in Growing Networks, show for the first time how networks evolve optimising a unique trade-off between popularity and similarity. They found that while popularity attracts new connections, similarity is just as attractive.

''Popular nodes in a network, or those that are more connected than others, tend to attract more new connections in growing networks,'' said Dmitri Krioukov, co-author of the paper and a research scientist with SDSC's CAIDA group, which studies the practical and theoretical aspects of the Internet and other large networks.