Alvin E. Roth and Lloyd S. Shapley: Stable allocations and the practice of market design

Economists study how societies allocate resources. Some allocation problems are solved by the price system: high wages attract workers into a particular occupation, and high energy prices induce consumers to conserve energy. In many instances, however, using the price system would encounter legal and ethical objections. Consider, for instance, the allocation of public-school places to children, or the allocation of human organs to patients who need transplants. Furthermore, there are many markets where the price system operates but the traditional assumption of perfect competition is not even approximately satisfied. In particular, many goods are indivisible and heterogeneous, whereby the market for each type of good becomes very thin. How these thin markets allocate resources depends on the institutions that govern transactions.