We survey the literature on social networks by putting together the economics, sociological and physics/applied mathematics approaches, showing their similarities and differences. We expose, in particular, the two main ways of modeling network formation. While the physics/applied mathematics...

We develop a model of competing diffusions of goods on a social network. There are two types of goods and individuals: mass-market (more prevalent) and niche-market. We start with a general threshold rule and show that multiple equilibria prevail. Then, when everyone uses a single friend...

We develop a model where, in the first stage, minority individuals have to decide whether or not they want to assimilate to the majority culture while, in the second stage, all individuals (both from the majority and the minority group) embedded in a network have to decide how much effort they...

We study how friendship shapes students' political opinions in a natural experiment. We use the indicator whether two students were exogenously assigned to a short-term \integration group", unrelated to scholar activities and dissolved before the school year, as instrumental variable for their...