RECENT DEVELOPMENTS IN THE THEORY OF NATURAL MONOPOLY
综述了自然垄断理论的两大新进展：Baumol等人对多产品成本和社会效率的澄清，以及Shaked和Sutton基于消费者收入分布的垂直产品差异化与自然寡头理论。
Abstract. This paper examines two important recent developments in the theory of natural monopoly, or more generally the theory of market structure. The first is a series of papers, involving Baumol with various co‐authors, investigating the theory of industry structure, whilst the second is particularly associated with the names of Shaked and Sutton, and the relationship they develop between product differentiation and industry structure. The paper surveys and to some extent contrasts these two new approaches. Baumol et al. 's contribution is seen to be in the area of clarifying the concept of natural monopoly, refining the definitions of multiproduct costs, and developing a notion of social efficiency applicable to industries where economies of scale are important. Shaked and Sutton employ a new definition of natural monopoly unrelated to market size and utilize information about consumers’income distributions to develop their notion of vertical product differentiation and natural oligopoly.