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Introduction to Complex Systems and Social Network Analysis
Arif KhanComplex Systems Research Centre
The University of Sydney
Lecturer (on leave)Department of CSE, BRAC University
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
What is Social Networks
• Relationship between Social Entities
A B
CD
Nodes are Entities/ActorsCan be people, organization, countries
Edges are relationshipCan be Friendship, Transaction, Trust, Relationship
Some Social Network
• Migratory Bird Network
Some Social Networks• Relationship network in a U.S. high school. Girls are pink, boys
are blue
Some Social Network
• Ingredients Network
Why Social Network Analysis?
• Because our choice/behavior has social context, we are influenced by others
Some Research Facts
• Relationships are mostly mutual. If you like me, I will like you.
A B
• Friend of my friend will eventually be my Friend
A B
C
Some Research Facts
• Making and Maintaining friendship is costly.• Average person can maintain only 150
intimate relationship.• So this friendship network is hardly possible.
Some Research Facts
• This is a small world. On average each person of world has a friendship distance of 6
• There are on average 3.74 people in between any two facebook users.
Complex System
• Social Networks are one type of Complex System, they have all the properties discussed above.
• Complex Systems– Have large number of actors/nodes– Changes over time– They are resilient.
Centrality: finding important Nodes
• Degree Centrality
A B
C
D
E
I am So popular!!
A B
C
D
E
I am social,
I love
everyone!!
B has high in-Degree
B has high out-Degree
Centrality: finding important Nodes
• Betweenness Centrality‘A’ has high Betweenness centralityIt can control Information, can control business,Can manipulate information
Centrality: finding important Nodes
• Closeness centralityI may not have
lots of friend. But I have powerful
friend, enough for me
High (not highest) closeness centrality
Example of SNA software (Gephi)
• Analyze my Facebook network• <OPEN GEPHI outside>
Social Network Analysis as CSE perspective
• Developing efficient algorithms (graph algorithm, approximation algorithm)
• Developing efficient graph/mathematical models of real world Social Networks
• Developing data mining software, centrality measures
• And many more…
If you are interested…
• This is relative new research area.• Almost all universities have research centers
related to Social Network analysis, complex system, data mining etc.
• Complete the online course (FREE!) from www.coursera.org/course/sna
THANK YOU
Questions?
Important Links: www.coursera.org/course/snaMy Mail: [email protected]
Pictures taken from various sources, may be copyrighted. Used for Educational purpose only