I am confused about 'single' vs 'multiple' agent reinforcement learning. Let's say that I have 1 hunter who I am training to hunt 1 static prey, so that only the hunter is moving around. This is definitely single-agent RL. If there are two hunters and two preys (moving or static), then this becomes multiple agent RL. It would be 'easier' to study two independent hunters, perhaps, but that is a different problem. My question is this: If there is 1 hunter only, but there are two preys. There is 'some form of interaction' (vaguely defined) between the hunter and prey. Is this still a single-agent RL? or a multiple one? Is it possible that my agent is the hunter, and all preys be just part of the environment? 
single agent vs multiple agent reinforcement learning
machine learning;learning theory;reinforcement learning