Never underestimate the power of emergent behavior of a small number of interacting rules. The ghosts do not have to explicitly interact in order for them to co

Never underestimate the power of emergent behavior of a small number of interacting rules. The ghosts do not have to explicitly interact in order for them to coordinate. The fact that a ghost blocks scent means that they influence each other in a way that leads to them covering multiple paths. I'm not an expert, but I would bet hard cash that such a strategy works better than any explicit coordination strategy that takes up to an order of magnitude more effort to implement, and I wouldn't be surprised if it's mathematically optimal.