Maximizing the Spread of
Influence through a
Social Network
Kempe, Kleinberg, Tardos 2003
Ellie Clougherty
Goal: Which subset of
individuals are the most
influential?
How can we select a subset
of nodes that will have the
greatest impact?
Name: Ellie Clougherty
Can you find
degree
centrality?
Can you find
distance
centrality?
Network Data
Co-authorships of high-energy physics papers
Node: Author
Edges: Degree of co-authorship
Goal: Select the most
influential nodes
An NP-Hard optimization problem!
Solution:
Naturally-greedy, hill-climbing, submodular
algorithm obtains 63% of the optimal solution
Two Models
Weight: Number of Edges / Co-Authorships
Linear Threshold Model
A node becomes active when the total
weight of it’s active neighbors exceeds a
random threshold
Independent Cascade Model
An activated node has one chance to
activate an inactive neighbor with a
weighted probability
Context Matters
 Consider the dynamics of information in a
network, not just the structure
 Weighting the influence of one node to another
depends on the context and nature of the data
Future Steps:
 Generalized Framework: combine both models
 Non-progressive models: activation is bi-
directional
Additional Sources
Node Grid:http://en.wikipedia.org/wiki/Centrality#mediaviewer/File:Centrality.svg
Indian Grid:http://www.mnn.com/earth-matters/energy/stories/whats-wrong-withindias-electric-grid
John Kelly Protesting: http://www.npr.org/2014/10/01/352757107/campus-sexualassault-law-now-includes-language-on-same-sex-violence
UVA Protestors: http://www.nytimes.com/2014/11/25/us/rocked-by-rape-reportuniversity-of-virginia-to-hold-special-meeting.html?smid=fbnytimes&smtyp=cur&bicmp=AD&bicmlukp=WT.mc_id&bicmst=1409232722000&bic
met=1419773522000
EM Slide:
http://sifaka.cs.uiuc.edu/~wang296/Course/IR_Fall/docs/PDFs/Language%20Mod
els%20II.pdf
Truthy: http://truthy.indiana.edu/
Business Insider: http://www.businessinsider.com/what-makes-an-article-go-viral-20125