Swarm Intelligence
Swarm Intelligence is a general term of the flexible, adaptive and collective behavior found in swarms, flocks, herds and other social groups, especially for social insect colonies such as ant or termites colonies, or colonies of wasps, bumble and honey bees.
Definition and History
Swarm Intelligence is traditionally understood as "the emergent collective intelligence of groups of simple agents" (Bonabeau et al. 1999). It is the typical example of emergence and emergent phenomena. The expression "swarm intelligence" was introduced by G. Beni and U. Wang in 1989, in the context of cellular robotic systems. In these systems many simple agents occupy one- or two-dimensional environments to generate patterns and self-organize through nearest-neighbor interactions. Bonabeau, Dorigo and Theraulaz extend Beni et al.'s definition in their "Swarm Intelligence" book, and include any attempt to design algorithms or distributed problem-solving devices inspired by the collective behavior of social insect colonies and other animal societies.
Forms and Relations
The concept of swarm intelligence is related to the two basic concepts of stigmergy and emergence, which describe the appearance of organized behavior patterns in groups of individuals. Coordination of collective behavior is not possible without communication. This communication is of course not always evident and visible. Sometimes the communication takes place in a direct way (for example by visual contact), sometimes the communication happens indirectly with the help of the environment (for example by invisible scents).
There are two basic forms of swarm intelligence: (1) swarm-formation and (2) stigmergy. The term swarm-formation describes the first basic form of swarm intelligence and characterizes the creation of swarms, flocks or groups by direct interaction, as it can be observed in flocks of birds, schoals of fish, etc. The rules are simple: stay close to the group, but don't come too close to individuals. The principle of swarm formation is based on a distinction between global and local, group and agent, swarm and individual: global attraction (move towards the group) combined with local repulsion (stay aways from individuals).
Stigmergy is the second basic form of swarm intelligence. Swarm intelligence and stigmergy are often used synonymously and describe swarms and groups which are controlled by indirect interaction over the environment, for example in ant-based systems. Emergence is the general term which describes the appearance of macroscopic phenomena out of mircoscopic interactions.
Examples
Large animal groups with coordinated movement such as swarms, herds, schools, and flocks are widespread phenomena in biology. These coherent, large-scale groups often bring negative consequences for the individual (increased competition for resources, disease transmission, and attention from predators), but also benefits (more effective foraging, reproduction, migration, diluting the chance of capture and escape from predators).
The advantage a swarm offers is often in a delicate balance by a disadvantage. The swarm can detect a predator better than an individual, but the predator can also detect a swarm better than a individual animal. A swarm can detect a food source better than an individual, but it also exploits it much faster than any individual
The coordination relies often on a kind of language. Honeybees perform a dance on their return to the hive, known as bee dance or waggle dance. The information contained in this "dance language" is used to select a new nest site or to exploit a new food source. Ants and other insects communicate mainly through "chemical languages": pheromones and other chemical scents and substances.
- nest building of social insects (wasps, termites: pheromones)
- path finding and food foraging (ants, locusts: pheromones)
- nest site search and nectar foraging (honey bees: waggle dance)
- collective sorting and clustering (ants: change of environment,stigmergy)
- group defense
Among locusts (grashoppers) swarming behaviour is partially a response to overcrowding. When large numbers of locusts are forced together in a small area, they being to form a swarm that can travel long distances consuming lots of vegetation. The critical tipping point is around 20 insects per square metre. Swarms of locusts can be a plague, because they consume vast amounts of crops.
A swarm of locusts allows more effective migration and travel. Each member of the swarm expends less energy than a single locust would spend in normal individual flight. Contrary to individual locusts, locust swarms can travel up to 100km or more in a single day.
Scientists
Software and Optimization
Software and Hardware:
Hardware and Robotics:
Biology
Articles
Many articles and resources can be found here.
G. Beni and U. Wang, Swarm intelligence in cellular robotic systems, In NATO Advanced Workshop on Robots and Biological Systems, Il Ciocco, Tuscany, Italy, 1989.
Stable Flocking of Mobile Agents, Part I: Fixed Topology Herbert G. Tanner, Ali Jadbabaie and George J. Pappas, 2003
Stable Flocking of Mobile Agents Part II: Dynamic Topology Herbert G. Tanner, Ali Jadbabaie and George J. Pappas, 2003
Designing and Understanding Adaptive Group Behavior Maja J. Mataric, 1995
Dance languages and nest site search of honey bees
- How Self-Organization Evolves, P. Kirk Visscher, Nature Vol. 421 (2003) 799-800
- Collective decisions and cognition in bees, P. Kirk Visscher, Scott Camazine, Nature Vol. 397 (1999) 400
- Dance Language, P. Kirk Visscher, in V.H. Resh and R. T. Cardé, eds. Encyclopedia of Insects. Academic Press (2003) pp. 284-288
Books
- Marco Dorigo, Thomas Stützle, Ant Colony Optimization (2004) The MIT Press, ISBN 0262042193
- Eric Bonabeau, Marco Dorigo, Guy Theraulaz, Swarm Intelligence: From Natural to Artificial Systems (1999) Oxford University Press, ISBN 0195131592
- Scott Camazine et al., Self-Organization in Biological Systems (2003) Princeton University Press, ISBN 0691116245
- James Kennedy and Russell C. Eberhart, Swarm Intelligence, (2001) Morgan Kaufmann, ISBN 1558605959
- Mitchel Resnick, Turtles, Termites, and Traffic Jams: Explorations in Massively Parallel Microworlds (1997) The MIT Press, ISBN 0262181622
