Presented by: 
Professor Andrew D. Barbour (Melbourne)
Mon 16 Apr, 2:00 pm - 3:00 pm
N201 in Hawken (50)

In the modern world, social and casual contact can be described as a mix of regular local contact, supplemented by occasional long-range contact.  The SARS epidemic, for instance, presented a number of foci that were widely separated in space, presumably for precisely this reason. There have been a number of different models advanced that reflect this idea:  the Watts-Strogatz "small worlds" model of social interaction, the Ball, Mollison and Scalia-Tomba "great circle" model of infection, and the Aldous model for the spread of gossip.  In this talk, we show that these models are all closely linked mathematically, with branching processes being the common feature, and that, perhaps surprisingly, branching processes can be used to deliver a broad description of the whole course of their spread, and not just of the early stages of development.