Archive for February 16th, 2012

PageRank in the Science of Links

Thursday, February 16th, 2012 by Antonio Manzalini

Imagine a library containing billions of books without any centralized organization and librarians. Anyone may add a document at any time. How would you access a piece of information in a few seconds ? It looks like the search on the WWW.

Search engines, like Google, have computer programs retrieving pages from the web, indexing the words in each document, and storing this information in an efficient format. This means that, for most searches, the result will be a huge number of pages. What is needed is a means of ranking the importance of the pages so that the pages can be sorted. One way to determine the importance of pages is to use a human-generated ranking. This is what “PageRank” does.

“PageRank” is a link analysis algorithm used by the Google that assigns a numerical weighting to each element of a hyperlinked set of documents with the purpose of “measuring” its relative importance within the set (source,

Amazingly PageRank can be used also in Computational Chemistry.

Researchers at Washington State University have realized that the interactions between molecules are similar to links between Web pages. They have adapted Google’s PageRank to understand how molecules interact. PageRank algorithm is particularly efficient and capable of looking at a massive amount of Web pages at once; similarly, it has been used to characterize quickly the interactions of millions of molecules and help Researchers predict how various chemicals will react with one another.

PageRank adapted for Computational Chemistry

This is a nice example of Industrial Mathematics cross-fertilization: an algorithm, invented for search on the Web, is adapted and used by Computational Chemistry.

Any further cross-applications ? Well, Chemistry (loosely speaking) is studying the dynamics of atomic units, self-aggregating by attractions and bonds, in a constant flurry of motion and change. Replace the atomic units with nodes (devices, smart objects, sensors, machines,…) of future networks and think about their self-aggregation for fleeting into networks in a highly dynamical environment…