EME: Emergence Module

1. EME: Emergence Module Susan Stepney susan@cs.york.ac.uk Fiona Polack fiona@cs.york.ac.uk

2. What is an emergent system? • Many simple elements, no central control • Overall behaviour that is not an obvious consequence of behaviour of elements • Construction by insects • Crowd or flock behaviour by people, birds, insects • Plants grown using simple growth algorithms • Animals developed from simple cells

3. Why study emergent systems? • Emergent systems cannot be understood by direct extension of conventional systems ideas • An emergent system is a system of systems • Emergent properties at system level • Components at system level* • Emergence requires a change in scale • Small systems combine to larger-scale effect * This will not make sense if you are colour-blind or reading in b/w!

4. How can an emergent system be engineered? • Through studying lots of emergent systems • We’ll cover various sorts in EME • By considering levels and the environment • Polack and Stepney work on architectural aspects of emergent system development • Through simulation and real-world observation • What needs to be modelled to faithfully simulate emergence? • Paying attention to dependability assurance…

5. What will we look at?

6. 2 1 0 0 0 0 3 0 0 1 0 1 0 2 1 0 1 0 0 2 0 0 1 2 1 0 0 3 2 1 0 0 2 3 2 0 1 2 3 2 2 0 1 3 2 1 0 0 3 1 Time 2 0 0 0 1 0 2 ... ... Transition 0 0 0 0 0 1 2 3 Table rules 0 0 0 0 2 3 CA: demonstrate complex behaviour from simple rules • CAs Time 1 • Game Of Life CAs • http://www.math.com/students/wonders/life/life.html • Langton’s self-replicating loops • http://necsi.org/postdocs/sayama/sdsr/java/

7. What will we look at? • Demonstrations that complex behaviour emerges from multiple instances of simple systems: • L-systems • Aristid Lindenmeyer & Przemyslaw Prusinkiewicz • biological metaphor: plant branching growth • eg. a bud becomes a twig, a twig gains buds, …

8. What will we look at? • Demonstrations that complex behaviour emerges from multiple instances of simple systems: • L-systems • Aristid Lindenmeyer & Przemyslaw Prusinkiewicz • biological metaphor: plant branching growth • eg. a bud becomes a twig, a twig gains buds, … • a production replaces a parent module with a child module pn:symbol rewrite_string “bud”  “twig” p1 : B  T “twig”  “twig” “bud” “bud” p2 : T  TBB

9. What will we look at? • Demonstrations that complex behaviour emerges from multiple instances of simple systems: • L-systems • Aristid Lindenmeyer & Przemyslaw Prusinkiewicz • biological metaphor: plant branching growth • eg. a bud becomes a twig, a twig gains buds, … [Prusinkiewicz & Lindenmeyer, fig 1.24a, c, d, 1.10, 1.24f, 1.8]

10. What will we look at? • Demonstrations that complex behaviour emerges from multiple instances of simple systems • … and various other artificial complex systems

11. What will we look at? • Demonstrations that complex behaviour emerges from multiple instances of simple systems: • Nanotechnology • “molecular” nanotech • little things that make big things • Nanobot constructors and replicators Design for a fine-motion controller for molecular assembly - 3000 atoms, <1nm http://www.imm.org/

12. Engineering • Not much work has been done on engineering • Most artificial emergent systems are hacked • Conway’s Game of Life CA was discovered by playing with patterns on a GO board • Proposals for real-world nano-scale assemblers and disassemblers make engineering urgent • We’ll look at • Identifying and measuring emergence • Layers in emergent systems • Towards assurance-directed development frameworks