there had been more than fifty arrests of demonstrators as we left the square. The IMSI catchers had conducted a census of all the phones in the neighborhood that night and the back-end had opened tickets with the Ministry of Communications to pull all the calling records to produce a social graph and mark out highly connected nodes, then run an information-cascade analysis: that was a cute machine-learning trick that tried to identify leaders - formal or informal - by looking at people whose communications produced "cascades" of activity: Alice calls Bob, who then calls Carol and Dan and Eve and Faith, so Alice is the boss and Bob is her lieutenant

Cory Doctorow, Attack Surface