Communication among terrorist cells works much in the same way as Justin Bieber's Twitter account, according to mathematicians from Ryerson University in Toronto who have built a mathematical model of the way information spreads through these hierarchical networks. Their approach may give counterterrorism agents insight into terrorism hierarchies and allow them to predict terrorist attacks and sabotage networks before the attack plans can be carried out.

Terrorist networks are often arranged hierarchically, meaning information flows in one direction: top down, from one leader to many followers. This model is called a "directed network without cycles," or a "directed acyclic graph." [See also: Google Search Algorithm Models Cancer Spread]