Swarm intelligence

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Swarm intelligence (SI) is an artificial intelligence technique based around the study of collective behavior in decentralized, self-organized systems. The expression "swarm intelligence" was introduced by Gerardo Beni, Susan Hackwood, and Jing Wang in 1989, in the context of cellular robotic systems[1].

SI systems are typically made up of a population of simple agents interacting locally with one another and with their environment. Although there is normally no centralized control structure dictating how individual agents should behave, local interactions between such agents often lead to the emergence of global behavior. Examples of systems like this can be found in nature, including ant colonies, bird flocking, animal herding, bacterial growth, and fish schooling.

The application of swarm principles to large numbers of robots is called swarm robotics.

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[edit] Example algorithms

[edit] Ant colony optimization

Ant colony optimization or ACO is a metaheuristic optimization algorithm that can be used to find approximate solutions to difficult combinatorial optimization problems. In ACO artificial ants build solutions by moving on the problem graph and they, mimicking real ants, deposit artificial pheromone on the graph in such a way that future artificial ants can build better solutions. ACO has been successfully applied to an impressive number of optimization problems.

[edit] Particle swarm optimization

Particle swarm optimization or PSO is a global optimization algorithm for dealing with problems in which a best solution can be represented as a point or surface in an n-dimensional space. Hypotheses are plotted in this space and seeded with an initial velocity, as well as a communication channel between the particles. Particles then move through the solution space, and are evaluated according to some fitness criterion after each timestep. Over time, particles are accelerated towards those particles within their communication grouping which have better fitness values. The main advantage of such an approach over other global minimization strategies such as simulated annealing is that the large number of members that make up the particle swarm make the technique impressively resilient to the problem of local minima.

[edit] Stochastic diffusion search

Stochastic Diffusion Search or SDS is an agent based probabilistic global search and optimization technique best suited to problems where the objective function can be decomposed into multiple independent partial-functions. Each agent maintains a hypothesis which is iteratively tested by evaluating a randomly selected partial objective function parameterised by the agent's current hypothesis. In the standard version of SDS such partial function evaluations are binary resulting in each agent becoming active or inactive. Information on hypotheses is diffused across the population via inter-agent communication. Unlike the stigmergic communication used in ACO, in SDS agents communicate hypotheses via a one-to-one communication strategy analogous to the tandem running procedure observed in some species of ant. A positive feedback mechanism ensures that, over time, a population of agents stabilise around the global-best solution. SDS is both an efficient and robust search and optimisation algorithm, which has been extensively mathematically described.


[edit] Applications

Swarm Intelligence-based techniques can be used in a number of applications. The U.S. military is investigating swarm techniques for controlling unmanned vehicles. ESA is thinking about orbital swarm for self assembly and interferometry. NASA is investigating the use of swarm technology for planetary mapping. A 1992 paper by M. Anthony Lewis and George A. Bekey discusses the possibility of using swarm intelligence to control nanobots within the body for the purpose of killing cancer tumors. Artists are using swarm technology as a means of creating complex interactive systems or simulating crowds. Tim Burton's Batman Returns was the first movie to make use of swarm technology for rendering, realistically depicting the movements of a group of penguins using the Boids system. The Lord of the Rings film trilogy made use of similar technology, known as Massive, during battle scenes. Swarm technology is particularly attractive because it is cheap, robust, and simple.

The inherent intelligence of swarms has inspired many social and political philosophers, in that the collective movements of an aggregate often derive from independent decision making on part of a single individual. A common example is how the unaided decision of a person in a crowd to start clapping will often encourage others to follow suit, culminating in widespread applause. Such knowledge, an individualist advocate might argue, should encourage individual decision making (however mundane) as an effective tool in bringing about widespread social change.

[edit] References in popular culture

Swarm Intelligence-related concepts and references can be found throughout popular culture:

  • The Invincible, by Stanislaw Lem A rescue mission to a distant planet encounters a mysterious and dangerous colony of evolved, insectlike machines.
  • Prey, by Michael Crichton deals with the danger of intelligent nano-robots escaping from human control and becoming dangerous.
  • Wyrm, a novel by Mark Fabi deals with a virus developing emergent intelligence on the Internet
  • Jason X, a movie in the Friday the 13th series, had a swarm of nanobots repair Jason's damaged body.
  • Hacker and the ants, a book by Rudy Rucker on AI ants within a virtual environment
  • The Swarm, a novel by Frank Schaetzing about an ocean organism that has developed swarm intelligence and begins to eradicate humanity the same way humans are eradicating the oceans.
  • Ygramul, the Many -- she is an intelligent being consisting of a swarm of many wasp-like insects, a character in the novel The Neverending Story written by Michael Ende. Ygramul is also mentioned in a scientific paper Flocks, Herds, and Schools written by Knut Hartmann (Computer Graphics and Interactive Systems * Otto-von-Guericke-University of Magdeburg).
  • Allucination, a novel by Isaac Asimov about an alien insect-like swarm, capable of organization and provided with a sort of swarm intelligence.
  • In Olaf Stapledons 1931 science fiction novel Last and First Men there is an episode in which Earth is invaded by a swarm intelligence from Mars of tiny individual cells that communicate with each other by radio waves and that look like green fog.

[edit] Researchers

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[edit] See also

[edit] References

[edit] External links

[edit] Swarm simulation links

[edit] Tools for Studying Swarm Intelligence

  • Swistrack - A Tracking Tool for Multi-Unit Biological and Artificial Systems
  • AgentSheets - A visual programming authoring and visualization tool to build swams based on Antiobjects
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