Multiagent Systems

The people really like their swarms. Can't say that I blame them. I also find them a lot of fun to thing about and model. In any case, the New York Times has another article on insect swarms. Most interesting was Couzin's general (parametrized) model of swarming which might apply to various species and can be tweaked to generate different types of swarming and also lets a few individuals act as leaders of the swarm without using any communication. Conflicting leaders are dealt with by ignoring the least popular ones.

Two leaders may try to pull a swarm in opposite directions, and yet the swarm holds together. In Dr. Couzin?s model, the swarm was able to decide which leaders to follow.

?As we increased the difference of opinion between the informed individuals, the group would spontaneously come to a consensus and move in the direction chosen by the majority,? Dr. Couzin said. ?They can make these decisions without mathematics, without even recognizing each other or knowing that a decision has been made.?

You can get the original paper for all the mathematical details. I also found the following bit extremely amusing:

?Each cricket itself is a perfectly balanced source of nutrition,? Dr. Couzin said. ?So the crickets, every 17 seconds or so, try to attack other individuals. If you don?t move, you?re likely to be eaten.?

This collective movement causes the crickets to form vast swarms. ?All these crickets are on a forced march,? Dr. Couzin said. ?They?re trying to attack the crickets who are ahead, and they?re trying to avoid being eaten from behind.?

Now imagine them doing this in a circle.