المنافسة في نظرية كورنو

The Cournot model is an oligopoly where firms compete on quantity rather than price, producing homogeneous goods. Each firm assumes its rival's output is fixed when making decisions and chooses output to maximize profit where marginal revenue equals marginal cost. This contrasts with perfect competition and monopoly, where firms either have no market power or complete control over pricing.

The Nash equilibrium, or Cournot-Nash equilibrium, occurs when both firms settle on production levels where neither can increase profit by changing output unilaterally. In a two-firm example, each firm initially captures half the remaining market share, but over time they converge to each occupying one-third of total market share. At this stable point, neither firm has incentive to deviate from its output decision.

Reaction curves illustrate each firm's optimal output response given its competitor's production level. The intersection of two firms' reaction curves represents the Cournot equilibrium, where both firms have settled on profit-maximizing production levels. This graphical representation shows how firms' decisions depend on each other and where they reach a stable, mutually optimal outcome.

Each firm assumes its competitor's output remains constant to simplify its profit-maximization decision. This assumption allows firms to focus on their own output choice based on marginal revenue equaling marginal cost. Although unrealistic, this framework helps model how firms interact strategically and eventually reach equilibrium through repeated adjustments.

Firms indirectly determine price through their output choices rather than setting prices directly. Since both firms offer identical products, total market supply influences the price. When one firm increases output, total supply rises, lowering prices and reducing revenue per unit. Conversely, reducing production increases prices, potentially benefiting competitors if demand is sufficiently inelastic.

When one bakery increases output, total supply rises, causing prices to fall and reducing revenue per loaf for both bakeries. If a bakery reduces production, prices increase, potentially benefiting the competitor—but only if demand is sufficiently inelastic. Both bakeries determine output based on marginal revenue considerations to maximize profit while maintaining market stability.

Firms in Cournot competition are interdependent; each company's output decisions directly impact others' profitability and market conditions. The choices made by one firm influence the other's optimal response, creating a steady, predictable situation where neither firm can gain advantage without triggering a competitive reaction. This interconnection drives both firms toward equilibrium.