垄断的经济学分析（公平交易法展示课）
什么是完全竞争perfectly competitive market
特点有2个，其实有很多。。。characters: 1是c很多买方卖方参与定价many buyers and sellers, all of whom are price-takers. 2是产业输出是标准的ii. An industry output is standardized.
产生非完全竞争的原因Reasons of distortion：参与者的限制Limitations in the number of producers和产品多样性的缺少Product differentiation
第一种非完全竞争：垄断！
Monolopy: a monopolist is a firm that is the only producer of a good that has no close substitutes. Only one product, no product differentiation.
特征：垄断者可定价i. Has market power to raise price.控制产品数量Will raise price and reduce production
产生原因是有准入障碍Cause: barriers to entry，4种障碍
1. Control of a scarce resource稀有资源
2. Economies of scale. 规模化的经济体
a. A natural monopoly emerges when LRATC (Long-Run Average Total Cost (LRATC)) [1]curve is declining.
b. Emere when there are large fixed costs associated with production.（Common ex. Local utilities ）
3. Legal barriers to entry.法律准入障碍（专利和著作权）
a. 1. Protection of IP (copyright and patent). 2. Government franchise.
b. Public interests is best served by a single seller in the market.
4. Network externalities. 关系网
a. An increase in networks membership increases its value to current and potential members. More beneficial to join a big one than a small one.
b. Once joined in, avoid switching cost.
c. Ex. Computer operating system. Phone service.
Maximizing Profits
If you find it counterintuitive that producing where marginal revenue equals marginal cost will maximize profits, working through the numbers will help.
Step 1. Remember that marginal cost is defined as the change in total cost from producing a small amount of additional output.
MC=change in quantity producedchange in total cost
Step 2. Note that in Table 3, as output increases from 1 to 2 units, total cost increases from $1500 to $1800. As a result, the marginal cost of the second unit will be:
MC=($1800−$1500)/1=$300
Step 3. Remember that, similarly, marginal revenue is the change in total revenue from selling a small amount of additional output.
MR=change in total revenue/change in quantity sold
Step 4. Note that in Table 3, as output increases from 1 to 2 units, total revenue increases from $1200 to $2200. As a result, the marginal revenue of the second unit will be:
MR=($2200−$1200）/1=$1000
垄断对消费者的伤害：
另外还存在一种价格歧视垄断
price discriminating monopolist that charge different prices to different customers. Price discrimination occurs when a firm charges different prices to different customers for reasons other than differences in costs.
three conditions must be satisfied
1 Must be a downward-sloping demand curve for the firms output
2 Firm must be able to identify consumers willing to pay more
3 Firm must be able to prevent low-price customers from reselling to high-price customers Price discrimination does not necessarily harm consumers nor does it necessarily cause inefficiency
第二种形式：垄断性的竞争：类似垄断
定义：Monopolistic competition: there are many producers, but the products they produce are not identical in the eyes of consumers. Restaurants
第3种：寡头垄断
Oligopoly. A market controlled by few producers
但寡头垄断是不稳定的，因为存在囚徒困境博弈
什么是LRATC [1] the lowest costs that a company will be able to reach for any degree of output over time
The first iterations of product development and assembly carry costs that will largely be greater at the onset. As more factories and production lines are introduced, the nature of costs shifts more towards the ongoing manufacture of the product. The burden of those expenditures diminishes as it becomes easier for the company to repeat and replicate its operations.
Eventually, the company will experience constant returns to scale as it pushes closer to peak efficiency. Cost of acquisition for raw materials can be reduced by making such purchases in increasingly growing quantities. Furthermore, the processes the company uses to make its product can become more stable and streamlined as it develops a rhythm and pace for its production flow.
If the company continues to scale up production, it will reach the part of the curve where diseconomies of scale become a factor and costs rise. Though a company might streamline operations, it might see new layers of bureaucracy and management introduced, which can slow overall production and decision making. The more the operation grows at this stage, costs will rise as the operation loses efficiency.
