The rules need to be reactive to the changes in the environmental state and the agent should be able to adapt to the changes autonomously and continue to perform its function. This behavior is called stigmergy. Without this property, the agent cannot be self-organizing and will require a centralized controlling agent. With stigmergy, the agent is made aware of the context within which it is operating even if the environment changes from the agents' previous interaction with it.
Take, for example, an ant moving on a path to the food source and there is some water poured on the path. As soon as the ant encounters water on the way, it starts looking for an alternate path based on the pheromone signal. It may also traverse its way back ...
