We study the formation of coalitions that provide public goods to members. Individuals are linked on a tree graph and those with similar preferences are connected on the tree. We present a solution that selects allocations belonging to the coalition structure core and that are also envy-free.

Many local public goods are provided by coalitions and some of them have network effects. Namely, people prefer to consume a public good in a coalition with more members. This paper adopts the Drèze and Greenberg (1980) type utility function where players have preferences over goods as well as...