Course Introduction and Overview

Networked Life CSE 112 Spring 2006 Prof. Michael Kearns

Internet, Router Level • A purely technological network?

• “Points” are physical machines • “Links” are physical wires • Interaction is electronic • What more is there to say?

• Points: power stations • Operated by

companies

• Connections embody

business relationships

• Food for thought: – 2003 Northeast blackout North American Power Grid

Gnutella Peers • Points are still machines… but are associated with may depend on • Food for thought: “free riding”

people

• Links are still physical… but

preferences

• Interaction: content exchange

Foreign Exchange • Points: sovereign nations • Links: exchange volume • A purely virtual network

• Purely biological network • Links are physical • Interaction is electrical • Food for thought: – Do neurons cooperate or compete?

The Human Brain

The Premise of Networked Life

• It makes sense to study these diverse networks together.

• The Commonalities: – Formation (distributed, bottom-up, “organic”,…) – Structure (individuals, groups, overall connectivity, robustness…) – Decentralization (control, administration, protection,…) – Strategic Behavior (economic, free riding, Tragedies of the Common) • An Emerging Science: – Examining apparent similarities between many

human

and

technological

systems & organizations – Importance of

network effects

in such systems • How things are

connected

• Details of

interaction

matters greatly matter greatly • The metaphor of

viral spread

• Dynamics of

economic and strategic

interaction – Qualitative and quantitative; can be very subtle – A revolution of measurement, theory, and breadth of vision

Who’s Doing All This?

• Computer Scientists – Understand and design complex, distributed networks – View “competitive” decentralized systems as economies • Social Scientists, Behavioral Psychologists, Economists – Understand human behavior in “simple” settings – Revised views of economic rationality in humans – Theories and measurement of social networks • Physicists and Mathematicians – Interest and methods in complex systems – Theories of macroscopic behavior (phase transitions) • All parties are

interacting

and

collaborating

Course Mission

• A

network-centric

examination of a wide range of social, technological, biological, financial and political systems • Examined via the tools and metaphors of: – computer science – economics – psychology and sociology – mathematics – physics • Emphasize the common themes • Develop a new way of examining the world

A Communal Experiment

• No similar undergraduate course • No formal technical prerequisites – greatly aided by recent books – publications in Science, Nature, etc.

– preliminary class demographics: • ~37% freshmen/sophomore • ~52% College/Wharton • Extensive web visualizations and demos • Extensive participatory in-class and out-of-class social experiments • Exercises in data analysis • Note:

Networked Life

is now approved to fulfill the College’s Quantitative Data Analysis Requirement • Also counts as an SEAS engineering elective course

Course Outline

The Networked Nature of Society

(~2 lectures)

• Networks as a collection of pairwise relations • Examples of (un)familiar and important networks – social networks – content networks – technological networks – biological networks – economic networks • The distinction between structure and dynamics

A network-centric overview of modern society.

Contagion, Tipping and Networks

(~2 lectures)

• Epidemic as metaphor • The three laws of Gladwell: – Law of the Few (connectors in a network) – Stickiness (power of the message) – Power of Context • The importance of psychology • Perceptions of others • Interdependence and tipping • Paul Revere, Sesame Street, Broken Windows, the

Informal case studies from social behavior and pop culture.

Introduction to Graph Theory

(~1 lecture)

• Networks of vertices and edges • Graph properties: – cliques, independent sets, connected components, cuts, spanning trees,… – social interpretations and significance • Special graphs: – bipartite, planar, weighted, directed, regular,… • Computational issues at a high level

Beginning to quantify our ideas about networks.

Social Network Theory

(~3 lectures)

• Metrics of social importance in a network: – degree, closeness, between-ness, clustering… • Local and long-distance connections • SNT “universals” – small diameter – clustering – heavy-tailed distributions • Models of network formation – random graph models – preferential attachment – affiliation networks • Examples from society, technology and fantasy

A statistical application of graph theory to human organization.

The Web as Network

(~2 lectures)

• Empirical web structure and components • Web and blog communities • Web search: – hubs and authorities – the PageRank algorithm • The Main Streets and “dark alleys” of the web

The algorithmic implications of network structure.

Towards Rationality: Emergence of Global from Local

(~1 lecture)

• Beyond the dynamics of transmission • Context, motivation and influence • The madness/wisdom of crowds: – thresholds and cascades – mathematical models of tipping – the market for lemons – private preferences and global segregation

Begin to connect to classical issues of human and societal behavior.

An Introduction to Game Theory

(~2 lectures)

• Models of economic and strategic interaction • Notions of equilibrium – Nash, correlated, cooperative, market, bargaining • Multi-player games • Evolutionary game theory – mimicking vs. optimizing • Network effects • Social choice theory

Powerful mathematical models of what happens over links in competitive and cooperative settings.

Interdependent Security and Networks

(~1 lecture)

• Security investment and Tragedies of the Commons • Catastrophic events: you can only die once • Fire detectors, airline security, Arthur Anderson,…

Blending network, behavior and dynamics.

Network Economics

(~2 lectures)

• Buying and selling on a network • Modeling constraints on trading partners • Local imbalances of supply and demand • Preferential attachment, price variation, and the distribution of wealth

The effects of network structure on economic outcomes.

Behavioral Economics

(~1 lectures)

• What’s broken with economics and game theory?

• How should you split 20 dollars?

• Beauty contests and ultimatums • Cultural and sociological effects • The return of context • Guilt, envy and altruism: improving the theory

Controlled social psychology experiments examining how “rational” we really are(n’t).

Internet Basics

(~1 lecture)

• IP addresses • Routers • Domain Name Servers • ISPs • Congestion control, load balancing • The Web and URLs • Security issues, network vulnerability

Under the hood of the quintessential modern technological network.

Internet Economics

(~2 lectures)

• Selfish routing • The Price of Anarchy • Peer-to-peer as competitive economy • Paris Metro Pricing for QoS • Economic views of network security

The collision of network, economics, algorithms, content, and society.

Modern Financial Markets

(~2 lectures)

• Stock market networks – correlation of returns • Market microstructure – limit and market orders – order books and electronic crossing networks – network, connectivity and data issues • Quantitative trading – VWAP trading, market making – limit order power laws • Herd behavior in trading • Economic theory and financial markets • Behavioral economics and finance • Impacts of the Internet on financial markets

A study of the network that runs the world.

Course Mechanics

• Will make heavy use of course web page: – www.cis.upenn.edu/~mkearns/teaching/NetworkedLife – You will need good Internet access!

• No technical prerequisites!!! • Lectures: – slides provided; emphasis on concepts – frequent demos, visualizations, and in-class experiments – please be on time to lectures! (12PM) • No recitations • Readings: mixture of general audience writings and articles from the scientific literature • Three required texts: – “The Tipping Point”, Gladwell – “Six Degrees”, Watts – “Micromotives and Macrobehavior”, Schelling • Assignments (~1/4 of grade) – data analysis: network construction project – computer/web exercises, short essays, quantitative problems – collaboration is

not

permitted • Participatory social experiments (~1/4 of grade) – behavioral economics experiments – analysis of experimental results • Midterm (~1/4 of grade) • Final exam (~1/4 of grade)

First Assignment

• Due

next lecture

(Th 1/12) – Simple background questionnaire – Last-names exercise