• How does Google find what you want?
• How do tolerant populations become segregated?
• How many friends between you and Kevin Bacon?
• How should you split $20 with a stranger?
• What can the Internet learn from Paris subway?
• How is file downloading like a competition?
• How might we combat spam economically?

• Examining apparent similarities between many human and technological systems & organizations
• Importance of network effects in such systems
• How things are connected matters greatly
• Structure, asymmetry and heterogeneity
• Details of interaction 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
– breadth of vision

• 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

• 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

• No similar undergraduate course
• No formal technical prerequisites
– greatly aided by recent books
– publications in Science, Nature, etc.
• Extensive web visualizations and demos
• Extensive participatory in-class social experiments
• Exercises in data analysis
• Note: Networked Life is now approved to fulfill the College’s
Quantitative Data Analysis Requirement

(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
• Models of network formation
A network-centric overview of modern society.

(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
Appeal of Smoking, and Suicide Epidemics
Informal case studies from social behavior and pop culture.

(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.

(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.

(2 lectures)
• Empirical web structure and components
• Web and blog communities
• Web search:
– hubs and authorities
– the PageRank algorithm
The algorithmic implications of network structure.

(2 lectures)
• Beyond the dynamics of transmission
• Context, motivation and influence
• The madness 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.

(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.

(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.

(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.

(2 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).

(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.

(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.

(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.

• 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 this term
• 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)
– course social network
– behavioral economics experiments
• Midterm (1/4 of grade)
• Final exam (1/4 of grade)

• Due next lecture (Th 1/13)
– Simple background questionnaire
– Last-names exercise