CS 346U

Exploring Complexity in Science and Technology

Instructor: Melanie Mitchell

Textbook: M. Mitchell, Complexity: A

Guided Tour(Oxford University Press)

• Note: All slides for a lecture will be available on the class webpage before each lecture:

http://www.cs.pdx.edu/~mm/ExploringComplexityFall2011

What are Complex Systems?

Large networks of simple interacting elements,

which, following simple rules, produce emergent,

collective, complex behavior.

What are Complex Systems?

Insect colonies

video1

video2

Brains

video

Immune systemvideo (+47sec.)

Economies

Schweitzer et al., Science, 325, 422-425, 2009http://www.sciencemag.org/cgi/content/full/325/5939/422

Food webs

Genetic Regulatory Networks

http://www.ibiblio.org/hhalpin/homepage/presentations/de2007/webearth.jpg

World-Wide Web

Social Networks

http://www.facebook.com/notes/facebook-engineering/visualizing-friendships/469716398919

http://cognitivecities.com/

http://www.nature.com/nature/journal/v467/n7318/full/467912a.html

Cities

Do these systems have anything in common?

Central question for the sciences of complexity

How do large networks with

— simple components— limited communication among components — no central control— simple rules of operation

give rise to complex (“adaptive”, “living”, “intelligent”) behavior, involving

— information processing and computation— complex pattern dynamics— evolution and learning?

Core disciplines of the science of complexity

Dynamics: The study of continually changing

structure and behavior of systems

Information: The study of representation,

symbols, and communication

Computation: The study of how systems process

information and act on the results

Evolution: The study of how systems adapt to

constantly changing environments

Goals of the Science of Complexity

• Cross-disciplinary insights into complex systems

• General theory

Methodologies

Methodologies

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Methodologies

Methodologies

Course Details

• Course web page:http://www.cs.pdx.edu/~mm/ExploringComplexityFall2011/

• Textbook: Mitchell, Complexity: A Guided Tour

• My office hours: T, Th 3-4pm

Netlogo

• We will use Netlogo to illustrate / experiment with complex systems ideas. Part of first assignment is to download Netlogo.

http://ccl.northwestern.edu/netlogo/

• Bring laptop to class if possible.

Assignments

• Weekly homework assignments: reading, writing, Netlogo

• Term project: – Build simulation in Netlogo

– Experiments using simulation

– Read 2 (or more) published paper related to topic of simulation

– Write term paper on simulation, results, related papers • 10-20 pages, double-spaced, including figures and

references

We will spend time in class learning Netlogo and formulating/working on final projects.

Grading

• Homework: 60%

• Term project and writeup: 40%

Class Rules

• Turn off cell phone

• During class, laptops are for taking notes, not for reading mail, chatting, web surfing, etc.

• While you’re here, make it worth your while. Pay attention.

• In return, class will be interesting enough to hold your attention! (I hope…)

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Introduction to Netlogo

“Pre-homework” assignment:

– Download Netlogo and Users Manual(You don’t have to print the manual)

– Try out some of the models in the Models Library

– Try to modify programs we wrote today (file will be on the class web page)

You don’t need to turn in anything for this.

Homework 1 assignment will be handed out on Wednesday.