文档介绍：Chapter Twenty-Seven
Oligopoly
寡头垄断
Structure
Non-collusive moves
Simultaneous moves
petition –Cournot model
petition – Bertrand model
Sequential moves
Quantity leadership – Stakelberg model
Price leadership
Collusion
Oligopoly
A monopoly is an industry consisting a single firm.
A duopoly is an industry consisting of two firms.
An oligopoly is an industry consisting of a few firms. Particularly, each firm’s own price or output decisions affect petitors’ profits.
Oligopoly
How do we analyze markets in which the supplying industry is oligopolistic?
Consider the duopolistic case of two firms supplying the same product.
petition
Assume that pete by choosing output levels.
If firm 1 produces y1 units and firm 2 produces y2 units then total quantity supplied is y1 + y2. The market price will be p(y1+ y2).
The firms’ total cost functions are c1(y1) and c2(y2).
petition
Suppose firm 1 takes firm 2’s output level choice y2 as given. Then firm 1 sees its profit function as
Given y2, what output level y1 maximizes firm 1’s profit?
petition; An Example
Suppose that the market inverse demand function is and that the firms’ total cost functions are
and
petition; An Example
Then, for given y2, firm 1’s profit function is
So, given y2, firm 1’s profit-maximizing output level solves
. firm 1’s best response to y2 is
petition; An Example
y2
y1
60
15
Firm 1’s “reaction curve”
petition; An Example
Similarly, given y1, firm 2’s profit function is
So, given y1, firm 2’s profit-maximizing output level solves
. firm 1’s best response to y2 is