Exchange Economies (revisited) No production, only endowments,so no description of how resources are converted to consumables. General equilibrium: all markets clear simultaneously. 1st and 2nd Fundamental Theorems of Welfare Economics

Structure Money equivalent of utility gains to trade Consumer's' surplus Changes in consumer's' surplus Compensating and equivalent variations Producer's' surplus

一、1(5分)当边际产量递减时,规模报酬也一定递减

Structure Utility function(效用函数) Definition Monotonic transformation(单调转换) Examples of utility functions and their indifference curves Marginal utility(边际效用) Marginal rate of substitution边际替代率 MRS after monotonic transformation

Structure Describing technologies Production set or technology set Production function Isoquant Marginal product Returns to scale Technical rate of substitution well- behaved technologies Long run and short run

Structure Types of cost curves Fixed, variable and total cost functions Average fixed, average variable and average cost functions Marginal cost functions Marginal and variable cost functions Marginal and average cost functions Short run and long run cost curves

Structure From Individual to Market Demand Functions Elasticities Revenue and ownprice- elasticity of demand Marginal revenue and price elasticity

Structure on -collusive- moves Simultaneous moves Quantity competition -Cournot model Price competition- Bertrand model Sequential moves Quantity leadership- Stakelberg model Price leadership Collusion

Mission of Economists Gary Becker: believe that the main purpose of economics is to understand and help to alleviate poverty\ Who are the poor? How can one help?

How Should a Monopoly Price? So far a monopoly has been thought of as a firm which has to sell its product at the same price to every customer. This is uniform pricing. Can price-discrimination-(差别定价 ) earn monopoly higher profits?