Information Cascades. Cascades. Information/behavior spreading through a network Useful for studying Actual viral contagion Technology diffusion, adoption of new products Cascading failures (e.g. power grids) Spread of information/rumor, viral marketing. How to model diffusion.
(weighted) θv fraction of its neighbors are active
Add node v to S that maximizes f(S +v) - f(S).
Fact: A non-negative linear combination of submodular functions is submodular