前面关于消费者和生产者行为的讨论，把价格当作所考虑的经济体的外生变量，消费者 和生产者都是既定价格体系的接受者。那么，这个既定的价格体系又是如何决定的呢？本章来 研究这个问题，价格将被当作经济系统的内生变量看待，由经济系统本身所决定。消费者与生 产者、需求与供给的共同作用，既决定了市场价格体系，又决定了各种商品的交易量，而且实 现了资源的最优配置，使社会福利达到帕累托最优。这就是本章将要得出的主要结论

从本章开始，我们将要研究经济活动者的行为如何影响商品价格的问题。本章讨论两种 极端情形的产品市场上厂商的行为及价格的决定问题，这两种理想的市场结构就是完全竞争和 完全垄断。尽管现实中很少能见到这样的市场，但它们对于揭示竞争和垄断的内在本质具有特 殊的重要意义

1. Course Objective This course is intended for those taking Prelims in Philosophy, Politics and Economics, Mods in Modern History and Economics, Prelims in Economics and Management and Part Is in Engineering, Economics and Management or Materials, Economics and Management

There are many different types of market structure. The main ones are: 1. Perfect Competition: Many small price-taking firms in an industry with free-entry. 2. Monopoly: One large price-setting firm in an industry with barriers to entry

Consumer surplus is a measure of how much money a consumer would need to be given, in order to be just willing to give up their entire consumption of a particular good. Consumer surplus is approximately the area behind the demand curve. The change in consumer surplus following aprice change is illustrated in the second graph

Suppose the consumer’s income were to increase. Optimal choice changes. How?

Consumers make choices over bundles of goods. Consumer theory models the way in which these choices are made. A good is simply a product — such as apples or bananas. A good may be specified in terms of time — such as

All the models considered so far have one thing in common. There is no uncertainty. This is a very restrictive assumption. Often in economic situations there is less than perfect information. Both production and consumption often involve unknown variables that affect the profits and utility of the agents

In the last lecture two concepts were introduced: Pareto efficiency and general equilibrium. How do they relate? Theorem: The first welfare theorem states that every general equilibrium involves a Pareto efficient llocation

Production — Oligopoly 1 Cournot Duopoly Suppose there are two firms in an industry. Their strategy spaces are quantities. Their payoffs are profits. Industry demand is given by the inverse demand function, P(Q), where industry production is Q = q1 + q2. They