Nonatomic congestion game

In a nonatomic congestion game, a divisible population chooses resources whose costs depend on aggregate usage. Each individual has negligible size, so changing their choice does not alter those costs. For traffic on a flow network, strategies are routes and an equilibrium is a Wardrop equilibrium: every route with positive flow has minimum delay for its source-sink pair. This differs from a finite-player congestion game, where a deviation changes the load used to evaluate the deviator's new cost. Continuous nondecreasing link delays give a Beckmann potential whose minimizers are exactly the traffic equilibria.