Today's topic was information diffusion in networks. There are many things that can influence the spread of information within a network. The three main factors in diffusion are network structure (degree distribution, clustering, connected components, etc.), strength of ties (frequency of communication and strength of influence), and spreading agents. A strong tie can be defined by frequent contact, affinity, or having many mutual contacts. One important study we looked at was about the strength of weak ties. Despite the name, weak ties can be very useful in spreading information. In the study, the author found that over 55 percent of people in the study found a job through a weak tie. They defined this weak tie as having contact with the person less than two times a week, but more than once a year.
In the lecture, we also discussed two key models for infection. These are SIR and SI. SIR stands for Susceptible -> Infected -> Removed/Recovered. Each node in the network can be classified by one of these terms in the SIR model. If a node is susceptible, then it can be infected. An infected node is self-explanatory. A removed node means it was infected and removed from the network. Or, a node can recover and build a natural immunity. The SI model is simply Susceptible -> Infected. The definitions remain the same, but a node is unable to recover and therefore remains infected.
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