COS 109: Computers in our World
• David Dobkin
dpd@cs.princeton.edu
(best way to reach me)
419 Computer Science Building,
office hours Mon 3:00-4:00 & Wed 3:00-4:00
or make an appointment
• COS 109 web site:
www.cs.princeton.edu/courses/archive/fall15/cos109
check this site often
(generally nothing on Blackboard)
• COS 109 TA’s
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Nayana Prasad Nagendra (nagendra@cs.princeton.edu), CS 226
Yichen Chen (yichenc@cs.princeton.edu), CS 313
Survey
• When did you get your first
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Personal computer
Smart phone
Tablet
Game box
iPod
• How many devices do you currently use
• Which of the following do you use and how often
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Word processing
Google (search, calendar, maps, … )
Email
Text messaging
Social networks (which ones)
Skype
Uber
Netflix
Survey (part 2)
• Have you heard of
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Random access memory
Moore’s Law
NP completeness
Javascript
Net neutrality
Spambots
The Cloud
The internet
TCP/IP
Malware/ransomware
• Have you held
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A transistor
An integrated circuit
A disk drive
Memory
A CPU
Why “Computers in our World"
• Computers have become ubiquitous
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computers & things they make possible are everywhere
changing our lives, at accelerating rate
lots of opportunities and good things
but also challenges, problems, tough issues
• An educated person should know the basics of computing
– Don’t need a technical course
– But need to deal intelligently in today’s world
• Secret agendas
– when you're running the country in 20 years, COS 109 will help you
do a better job
– This course satisfies the QR requirement and so we will be doing
some quantitative exercises
Components of the course
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Lectures
Labs
Problem sets
Readings
Class Discussion
Exams
QR exercises
Components of the course -- Lectures
Lectures – Monday and Wednesday 130—250
Attendance is important
Abstracted lecture notes to be posted after class
Components of the course -- Labs
• 8 labs:
– 2-3 hours/week + reading to
prepare
– labs start week of Sept 27 (posted
Sunday evening, due Friday midnight)
– You can do the labs on your own,
anywhere, any time
– There will be lab assistants to help,
in the Lewis Center (rooms 121 and
122)
Monday—Friday
7-11PM
Saturday
2-8PM
Sunday
5-11PM
• labs start week of Sept 27
Components of the course – Problem Sets
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8-9 problem sets: 1-2
hours/week
– the first one is posted, due
Monday Sept 28
• OK to discuss with classmates
– But you must identify
collaborators
– And everyone must do their
own write-up
Components of the course – Readings
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About 1 hour per week
– Do readings before class
• Text available at Labyrinth or
from Amazon
• Various readings
– Many of them historical
Components of the course – Class Discussion
So let’s have
And no
Components of the course -- Exams
• open-book take-home
midterm during midterm week
• open-book sit-down-in-abig-room final exam in
January
• Occasional in class short
quizzes
Components of the course – Quantitative Reasoning
• Quantitative reasoning is a process in which complex problems are
described mathematically and solved within a structured
mathematical framework. Courses in this area involve the
manipulation and interpretation of numerical and categorical
information and the quantification of inferences drawn from that
information. Appropriate courses include those that address
theoretical and empirical problems in the natural, social, computer,
and engineering sciences.
• The goal of courses in this category is to give students some
understanding of basic mathematical methods and their applications;
to provide them with an ability to understand and appreciate
quantitative issues that have become part of everyday life; and to
instill in them a lasting interest in quantitative methods and their
applications. Courses in this category are drawn from the
Departments of Computer Science, …
From: undergraduate announcement
Components of the course – Quantitative Reasoning
• Many problem sets will ask you to think quantitatively
• Some class time will be spent on quantitative thinking
• Goals
– To be able to think in numbers
– Not necessarily to get it right but to understand the right range
• Examples
– Are there closer to 5000 or 50,000 students at Princeton?
– If your disk has 4GB of memory, can you store hours or days of
music/video/…
– If everyone in the United States stands shoulder to shoulder, how
many times do they cover the perimeter of the country?
– And, an occasional – does this make sense?
What is wrong with this picture?
Grading (check the web page often!!)
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grading (approximately):
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20% problem sets + 20% labs + 20% midterm + 40% final
class participation helps; frequent absences will definitely hurt
remember that P/D/F has three possible outcomes
• A low score on the midterm and higher score on the final will
make the final count more
Grading Rubric
problem sets
labs
midterm
final
An approach to the course
• could teach course by picking a story or two from paper each day
– not "current events" but will use them a lot
• here are some I noticed over the summer
NYTimes August 3, 2015
WorldTruth.tv July 24, 2015
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NYTimes July 9, 2014
NYTimes June 4, 2015
NYTimes July 16, 2015
Other articles from a few days in the media
[ Things to notice ]
• pervasive computer systems; we depend on them completely
• complicated mixture of legal, political, economic, social issues
• running themes:
privacy & security
money & property
rights: individual, government, corporations
jurisdiction: who gets to decide
• things are changing at a rapid rate
• specifics are really new (most deal with things younger than you)
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Google is 17: founded in Sep 1998
Facebook is 11: founded in 2004
Twitter is 9: founded in 2006
iPhone is 8: appeared in 2007
Uber is 6; started in 2009
Pinterest is 5: appeared in 2010
Coursera is 3: April 2012
Lecture pauses
• I will make an effort to stop every lecture about halfway through
to discuss someone’s favorite website or app.
• A few of my favorite websites
– What's happening on the internet
– Battle of the Internet giants
[A quantitative exercise]
• How would we estimate the number of gas stations in America?
[A quantitative exercise]
• How would we estimate the number of gas stations in America?
• An approach
– There are 300 million people, maybe half have cars, each car needs
gas once a week …
– A gas station is open 12 hours a day and can service 20 cars an hour
– So, a gas station services 240 cars a day or about 1500 cars a week
– 150 million cars need to be serviced each week
– So, there are about 100,000 gas stations in America
[A quantitative exercise]
• How would we estimate the number of gas stations in America?
• A different approach
– Princeton has about 30,000 people and about 8 gas stations
– Princeton seems representative of the country as a whole
Fewer cars than California, more cars than New York City
– The US has 300 million people, so 10,000 Princetons
– So, about 80,000 gas stations in the country
[A quantitative exercise]
• Are our answers correct?
– Probably not precisely, but in the ballpark
There have to be more than 10,000; Why??
There can’t be as many as 1,000,000; Why?