Suppose they have a written contract, or even an unwritten contract, what enforces the contract for colluding firms or crooks in jail?

假如他们签了一份书面协议,或干脆口头的,他们怎么强制履行呢

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We know they can't sign a legal agreement, but let's take that off the table.

我们都知道不能签署违法合同,那就只能私底下签协议了

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What about you with your roommates?

那你和你室友是不是可以签协议

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So if the firms wanted to make more money, the only thing they could do is they could sign an agreement saying, why don't each of us produce not our Cournot quantity, but produce half monopoly profits.

所以如果你们想多赚钱,唯一能做的就是签协议,我们不要按古诺产量生产了,各自生产垄断利润的一半多好呢

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Well, one thing that goes wrong is that suppose Coke and Pepsi were able to either to write a contract or whatever to sustain joint monopoly output at this high price, this price which is actually producing positive profits in the industry it is going to turn out, therefore the price is going to be above costs.

我来说吧,问题出在这里了,假设可口可乐和百事达成了协议,不管签的是协议还是合同,只要能通过协约维持垄断产出,通过制定高价来达到正的利润就行,这样价格是高于成本的

耶鲁公开课 - 博弈论课程节选