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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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Emer introduction

EMER: Introduction

EMER is taught by

Susan Stepney

and Fiona Polack

Module structure

Module Structure

But first some introductory ideas

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



At the low level (here molecular or

nano-scale): particles do their thing

What is this?

Could be pretty much anything!



Behaviour is observable at a higher level –macro-scale

Particles are water molecules

– emergent effect is

flowing water

Wharfe, Burnsall, March 2006



Actual effects observed depend on things in the environment:


depth (volume of water)

gradient, etc.

Moselle, June 2006



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

Why study emergence

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

How will we study emergent systems

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]

How will we study emergent systems1

How will we study emergent systems?

Natural examples

Building – social insects

Networks – ants


Flocking – birds and fish http://www.fotosearch.com/PDS136/200351304-001/

How is emergence recognised

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)

How is emergence recognised1

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

Where might study of emergence lead

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.

Where might study of emergence lead1

Where might study of emergence lead?


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

How can an emergent system be engineered

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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