E   M   E   R   G   E    N   T  

What is Emergent Behaviour?

Economies - beehives - financial markets - animal markings -  team building -  consciousness - locust swarms - mass hysteria - geese flocking - road networks and traffic jams - bacterial infection - town planning - evolution - the Web ... these are all examples of emergent phenomena where a collection of individuals interact without central control to produce results which are not explicitly "programmed".

Qualities of Emergent Behaviour

What can emergent systems do that other systems can’t? 

  1. They are robust and resilient. There is no single-point of failure, so if a single unit fails, becomes lost or is stolen, the system still works.
  2. They are well-suited to the messy real world. Human-engineered systems may be “optimal” but often require a lot of effort  to design and are fragile in the face of changing conditions. Importantly, they don’t need to have complete knowledge/understanding to achieve a goal (e.g. social systems in warehousing).
  3. They find a reasonable solution quickly and then optimise. In the real world, time matters - decisions need to be taken while they are still relevant. Traditional computer algorithms tend to not produce a useful result until they are complete (which may be too late, e.g. if you're trying to avoid an oncoming obstacle) .

How it works 

The individuals interact with each other directly or indirectly (via their environment). Interacting via an effect on, and response to, their common environment is called stigmergy. For example, termites work together to build termite mounds without any "queen" to co-ordinate activity and without any pre-existing plan of what to build. They change the environment and the changed environment modifies their behaviour. For example, to build a single termite mound in an environment consisting of randomly-scattered wood chips, a group of termites each has only to follow one simple rule :

Whilst wandering randomly
	If you find a chip
		then pick it up
	unless you're already carrying a chip
		in which case drop it
             

To begin with, several small mounds will start to emerge, but then the largest mound will grow at the expense of the smaller ones until there is only the larger one left. This is because termites are more likely to find the large mound than the small ones. You can gain an intuitive understanding of this by downloading the StarLogo application by Mitchel Resnick of  MIT.

Interestingly, through emergent behaviour "selfish genes" can cause apparently social behaviour  By forming into schools (using simple emergent “flocking” rules), animals like fish and zebras reduce their individual chances of predation.

Applications

Which problems of today can emergent systems solve?

Who's working on this?

Much of the work is being done in the USA, especially at Santa Fe.

Work in the UK includes:

Bibliography

General References

Relevant Books

© 2003 Pilgrim Beart