Each controller is composed of distinct behavior components for pursuit and evasion. A player's fitness is based entirely on how well it performs in competition with several other players chosen randomly from the coevolving population of players. This approach avoids the need for an expert player as a fitness reference. In the beginning, the quality of play is very low. This provides a fertile field for slightly better strategies to exploit the weaknesses of others.
Some runs use mutation.
Robust behavioral control programs for a simulated 2d vehicle can be constructed by artificial evolution. Corridor following serves here as an example of a behavior to be obtained through evolution. A controller's fitness is judged by its ability to steer its vehicle along a collision free path through a simple corridor environment. The controller's inputs are noisy range sensors and its output is a noisy steering mechanism. Evolution determines the quantity and placement of sensors.