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EMER: Introduction

EMER: Introduction. EMER is taught by Susan Stepney and Fiona Polack. Module Structure. But first …some introductory ideas. Emergence Behaviour observed at one scale is not apparent at other scales Self-organisation Structures that emerge without systematic external stimuli Complexity

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EMER: Introduction

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  1. EMER: Introduction EMER is taught by Susan Stepney and Fiona Polack

  2. Module Structure

  3. But first …some introductory ideas • Emergence • Behaviour observed at one scale is not apparent at other scales • Self-organisation • Structures that emerge without systematic external stimuli • Complexity • On a continuum between totally ordered and totally random

  4. Emergence At the low level (here molecular or nano-scale): particles do their thing What is this? Could be pretty much anything!

  5. Emergence Behaviour is observable at a higher level –macro-scale Particles are water molecules – emergent effect is flowing water Wharfe, Burnsall, March 2006

  6. Emergence Actual effects observed depend on things in the environment: riverbed depth (volume of water) gradient, etc. Moselle, June 2006

  7. Emergence But there is minimal variation among particles Also, a few million fewer particles makes little difference to what is observed … and a few billion billion fewer just gives a slightly shallower river Troller’s Gill,, March 2006

  8. Science and engineering interest: An emergent system is a systemofsystems Emergent properties at system level Components at system level Emergence cannot be understood by looking either at the composed system or the component systems Why study emergence

  9. How will we study emergent systems? Simulation examples Components with simple rules – L-systems, CAs … Gosper’s CA glider gun : [Prusinkiewicz & Lindenmeyer, fig 1.24a, c, d, 1.10, 1.24f, 1.8]

  10. How will we study emergent systems? Natural examples Building – social insects Networks – ants http://iridia.ulb.ac.be/~mdorigo/ACO/RealAnts.html Flocking – birds and fish http://www.fotosearch.com/PDS136/200351304-001/

  11. How is emergence recognised? 1. Observation or description Cannot describe using the same terminology for component and emergent behaviours1 e.g. Game of Life CA glider: components are static coloured cells but glider is a moving block of one colour e.g. Pile of sand grains: size, mass, of pile are sum of grain values, but slope of pile emerges from combined behaviours of grains 1 But see Smith and Sanders’ work on formally demonstrating the link across levels: e.g. Jeff W. Sanders, Graeme Smith: Emergence and refinement. Formal Asp. Comput. 24(1): 45-65 (2012)

  12. How is emergence recognised? 2. Measurement (to some approximation) Information theoretic models of emergence Entropy and how it changes at different scales Postulated edge-of-chaos and its link to emergent behaviour Distinguishing emergent characteristics or types Clarifying similar concepts

  13. Where might study of emergence lead? Engineering emergent systems Realising Drexler’s vision of molecular nanotechnology used for constructing and repair Nano-scale construction is already viable Molecular nanotech. simulations are well developed Some form of engineered complex emergent systems exist at the macro-scale Human organisations, networking etc.

  14. Where might study of emergence lead? Simulation Scientific research into complex systems is difficult Observation perturbs the system “live” systems may be unobservable at the level needed Computer simulation may offer an alternative Platform for developing and exploring hypotheses Simulations must be developed and used in ways that support accurate interpretation of results

  15. How can an emergent system be engineered? In so far as we can answer this at all … Understand what emergence means studying lots of emergent systems Consider appropriate levels and views of system and its environment Work out how simulation can contribute What needs to be modelled What it tells us about reality Pay attention to assurance needs

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