Graph theory basics
A directed graph is a pair G = (V, E) where V is the set of
nodes in the graph, and E V V is the set of edges or links
in the graph.
In the definition above, edges have direction. The edge (a, b)
E does not imply that (b, a) E.
Graphs
Information Cascades
1
Following the crowd
Why do people get influenced by others and imitate others?
Is it just social pressure or can there be rational reasons for
them to do so?
2
Choosing a restaurant
Suppose you go to a new town and are debating b
Game theory
1
Theory to address situations where the outcomes of a persons
actions depend not only on how they choose among several
options, but also on the choices made by the people with whom
they interact.
Interconnectedness at the level of behavior in
Auctions
1
Types of auctions
Another application of game-theoretic ideas.
Two types of auctions:
Seller auctioning an item to a set of buyers (we focus
on this type).
Buyer tries to purchase an item and runs an auction
among a set of sellers (procurem
Cascading behaviour in Networks
1
Diffusion in networks
We considered how an individuals choices are affected by
the aggregate effects in the network.
But how do an individuals network neighborss choices influence her?
Many of our interactions happen a
Graph theory basics
A directed graph is a pair G = (V, E) where V is the set of
nodes in the graph, and E V V is the set of edges or links
in the graph.
In the definition above, edges have direction. The edge (a, b)
E does not imply that (b, a) E.
Graphs
Networks, Crowds, and Markets:
Reasoning about a Highly Connected World
David Easley
Jon Kleinberg
Dept. of Economics
Cornell University
Dept. of Computer Science
Cornell University
Cambridge University Press, 2010
Draft version: June 10, 2010.
2
Contents
Information networks
and the World Wide Web
1
The Structure of the Web
Application that was originally designed to let people share
information over the Internet
Created by Tim Berners-Lee in the period 1989-1991.
Users can make documents easily availa
COMP 691
Social and Information Networks
Instructor: Lata Narayanan
Office: EV 3.163
Office hours: Mondays 11-12
Email: lata@cs.concordia.ca
Webpage: users.encs.concordia.ca/lata
Course webpage: users.encs.concordia.ca/comp691 4
A number of pictures and i
1- Chapter 2, Question 3
To find a graph in which the diameter is more than three times as large as the average distance,
we need to increase diameter while the distances between other nodes are not very large. So,
the first thing that comes to the mind i