Users need to connect a pair of target nodes in the network. They share the fixed connection costs of the edge. The system manager elicits target pairs from users, builds the cheapest forest meeting all demands, and choose a cost sharing rule satisfying:

The celebrated "tragedy of the commons" arises when a certain technology with increasing marginal cost is the common property of its users. Examples include the exploitation of fisheries and other natural resources, as well as queuing problems where users want a service and the externalities...

In a rationing problem, each agent demands a quantity of a certain commodity and the available resources fall short of total demand. A rationing method solves this problem at every level of resources and individual demands. We impose three axioms: Consistency (with respect to variations of the...