1. The Power of Networks Six Principles That Connect Our Lives
Course Overview
Chien-Chung Shen

2. Why This Course? social networks, economic networks,
network services &
applications,
…….
1st edition in 2000
Computer Networks
- layers and protocols (TCP, IP, HTTP, etc.)
October 2016

3. Overview “Networks” are everywhere nowadays
e.g, who we are friends with on Facebook; how our s get carried through Internet in a matter of milliseconds
social, communication, economic, etc.
different functions: recommending movies to watch, controlling device power levels, and viralizing video clips
inner workings of these functions are six hidden principles that pop up in all different kinds of networks
This course discusses these six principles of “networking” that connect our lives
via basic arithmetic and supplemental materials
build intuition (with algebra)

4. Six Principles of Networking
Sharing is hard
Ranking is hard
Crowds are wise
Crowds are not so wise
Divide and conquer
End to end
Phrases that summarize the way “networks” are designed, built, and/or managed

5. Background & Lectures
CISC 450/650 are NOT pre-requisite for the course
Basic mathematics (algebra)
Interactive lectures via questions and answers

6. Part 1 Sharing Is Hard

7. Overview How network resources can be shared among many people?
Two wireless technologies
cellular
WiFi
What resources?
electromagnetic spectrum over “air”
Key approaches
managing interference
when to communicate
how loudly to communicate
pricing network usage smartly

8. Part 2 Ranking Is Hard

9. Overview
In Part 1, Sharing Is Hard, it is challenging to efficiently divide shared resources among users
Part 2, Ranking is Hard, how to find appropriate ranking of a set of items
Google’s two practices as examples
Two types of “pages”
ad spaces
bids from buyers (merchants)
search results
importance and relevance
PageRank algorithm

10. Part 3 Crowds Are Wise

11. Retail shopping, movie watching, and taking classes are daily activities impacted by Internet
eCommence of Amazon
content distribution of Netflix
MOOC (massive open online course) of Coursera
By doing these things online, we are contributing to an ever-increasing body of knowledge about peoples’ behaviors and preferences
When navigating websites, our actions are recorded and used to change experience of those who subsequently visit the sites
feedback for products on Amazon → ranking
rating for movies on Netflix → recommendation

12. How products are ranked on Amazon
how movies are recommended by Netflix
How people learn from one another in MOOC
Core idea → wisdom of crowds
As a crowd gets larger (more information collected), collective decision made by crowd will be better
higher-quality estimate on what truth is
Modeling of social networks
limitation of models in their explanatory and predictive capabilities
underlying assumptions of models

13. Part 4 Crowds Are Not So Wise

14. Everyone’s opinions are independent Two (research) questions to ask
Wisdom of crowds → aggregating information from a mass of people often results in better decisions than can be made by individuals
Inherent assumption?
Everyone’s opinions are independent
Two (research) questions to ask
In what situations will they not be independent?
What happens when they aren’t?

15. What other people think will influence your actions
watch that YouTube video because everyone was talking about it
buy iPad because everyone else has one
The more people you see that have followed through with such an action, the more temptation increases for you to do the same
Dependence of opinions in social networks
viralization
social influence

16. Part 5 Divide and Conquer

17. Divide and Conquer
Topics of previous chapters rely on existence of Internet
How is Internet designed, built, and managed?
One imperative property of Internet
scalability
because # of connected devices and sheer size of Internet constantly grow
How to achieve scalability?
efficient way to share network resources
division of management responsibility (both geographically and functionally) so that subparts can be tackled more easily
Scalable routing

18. Part 6 End to End

19. Congestion Control What is Internet? Internet Congestion control
a cloud
a black box
client and server communicate without knowing the details inside
Congestion control
find out how congested network is: how?
client sends something to server
client waits for responses from server
end-to-end (at C and S) by TCP
Distributed coordination among devices with back & forth acknowledgements
Internet

20. Social Networks Small world phenomenon
principle that we are all linked by “short” chains of acquaintances or “six degrees of separation”
Small Worlds and Six Degrees of Separation
The Science of Six Degrees of Separation
The six degrees: Kevin Bacon at TEDxMidwest