Cournot Duopoly 2D: Reaction Curves & Nash Equilibrium

This simulator renders the classic Cournot duopoly model as a 2D quantity-space map: two firms simultaneously choose output quantities, a single linear demand curve sets the market-clearing price, and each firm earns a profit that depends on both its own and its rival's output. The plane is colored by Firm 1's profit π₁(q₁,q₂), with a marker tracking the current outcome. Two reaction curves show each firm's best response to any quantity the other might choose, and their intersection — highlighted in gold — is the Cournot-Nash equilibrium. Run the best-response dynamics button to watch both firms alternately adjust toward that equilibrium, tracing a spiral path across the plane exactly as the reaction functions predict. Drag to pan and scroll to zoom the (q₁,q₂) plane at any scale.