Omid Rezvani (ANU) is speaking on "Community detection in large networks". The idea is that you can look at the links between people on-line to identify communities. This is typically used for targeted marketing: if someone in the identified group like a product, the others are likely to as well. Another use for the technology, I suggest, is to find people at risk of being recruited by terrorist groups (which the PM is concerned about). There has been some recent research on this.