A number of recent posts have been looking at models of how agents interact on networks, sometimes strategically and sometimes more simply. proneax discusses research on designing solutions to traffic congestion, in the spirit of our discussion of the Braess Paradox. This topic was also the focus of Tim Roughgarden’s research with Eva Tardos when he was a Ph.D. student here.

Fred Billups provides a very interesting simulation he created for a familiar experience — the way in which a few people packing up at the end of a large lecture class can trigger a large cascade of further students deciding to pack up. We’ll be talking a lot more about such cascading behavior later in the semester. Interestingly, in one of the papers we’ll be discussing — Mark Granovetter’s Threshold Models of Collective Behavior — the case of people leaving a lecture is actually explicitly invoked as an example. This type of packing-up phenomenon can also be viewed as an instance of synchronization, the subject of Steve Strogatz’s recent book Sync.

Finally, Aether discusses the game-theoretic aspects of voting — and particularly veto power — in the UN Security Council. The role of the veto in the Security Council was in fact one of the early motivating examples for the Shapley Value, a fundamental definition in the area of game theory.