Why Computer Science is a Great Choice

Why Computer Science is a
Great Choice
International Summer School, 2015

Ian Gent
• Ian Gent
• Professor
• School of Computer
Science
• http://ian.gent

International Summer School, 2015
Why Computer Science is a
Great Choice

Compared to Bologna for example

Wait a minute, how did I know that?

Computer Science is all about
Layers

Video by James Montgomery
St Andrews CS Student 2013-…
Won £3000 in National Contest!

How easy was it?
• To find out which is the oldest (western-style)
university in the world…
• Very easy…
– Call up a web search
– Go to the Wikipedia link
– Read the webpage
– Copy the image
– Insert it into the talk

How easy was it?
• To find out which is the oldest (western-style)
university in the world…
• Very easy…
– Call up a web search
– Go to the Wikipedia link
– Read the webpage
– Download the image
– Insert it into the talk

Call up a web search
• You know what web page I used, right….
• You know, that one everybody uses …
• You know, the one which often has a doodle …
• You know …

173.194.40.82
• The above is the “ip address”
• You might find it easier to call it Google
• Numerical address for the computer that did
the search
• But how did I get there from “google.com”
• Using Domain Name System (DNS)
– Translation from names to numbers
– Constantly updated

Domain Name System
• DNS didn’t have to happen
• Created by lots of hard work by great
computer scientists
Jon Postel Paul Mockapetris

How do you search the entire web in
half a second??
• With a LOT of careful preparation
• Start off by visiting all web pages in the world
– Yes all web pages
– As often as you possibly can
– And storing them all
– And that is the easy bit!
• Then figure out how to get them to users who want them
– On the first page of 10 hits out of 50 million
– This is called “Information Retrieval”

Information retrieval
• Find documents from words they contain
– University
• And from combinations of words
– Oldest university
• And maybe combinations never given to your
search engine before
• And with companies trying to make sure they get
their results first
– Even if it’s not the results the users want
• And in half a second

Information Retrieval
• Information Retrieval didn’t have to happen
computer scientists
Karen Spärck Jones Larry Page Sergey Brin

Go to the Wikipedia link
• Wikipedia….
– Who would have thought that you could get the
world to provide a massive encyclopedia for free?
– “Crowdsourcing” is mainly a feature of the
internet age
• Which came first, the Wiki or the Pedia?
– And you need the software to make the web
pages
– Wiki software, which Wikipedia was named for
• Not the other way round

Wikipedia
• Wikipedia didn’t have to happen
computer scientists (and financiers)
Ward Cunningham Jimmy Wales

Go to the Wikipedia link
• A link connects two pieces of text
– A type of HyperText
– Directed via a URL (Uniform Resource Locator)
– Transferred by HTTP (HyperText Transfer Protocol)
– Over the internet
• Remind me to tell you the time I printed out a
million digits of pi for my mother
– Which I found on “gopher”

Hypertext, URL, HTTP
• Hypertext didn’t have to happen
computer scientists
Vannevar Bush Ted Nelson Tim Berners-Lee

Read the webpage
• Uses language called HTML
– HyperText Markup Language
– Text but also instructions like links, emphasis etc
• Based on SGML (Standard Generalized
Markup Language)
– Originated in 1969, way before Web!
• We need a web browser to do this
– First major browsers were Mosaic & Netscape
– Let me tell you how good Netscape was

SGML, Browsers
• SGML & Browsers didn’t have to happen
computer scientists
Charles Goldfarb Marc Andreessen

Download the image
• We are need to get it over the internet
• There are a lot of wires between here & there
– And a lot of other computers
– And everything might be routed a different way
– And some packets might be lost
• Using the “Internet Protocol”
– IP Stack often pictured with 7 layers
• Yes just one bit of one aspect of this has 7 layers

The Internet
• Internet Protocols didn’t have to happen
computer scientists
Vint Cert talking to me (!!!) Bob Kahn

Download the image
• A lot of digital imaging is about compression
• I.e. compress a large file to make it smaller
• That’s why most images you see online are jpeg
or gif/png.
– jpeg uses lossy compression
• Lossy compression isn’t just maths, but critically uses
understanding of human perception
– gif/png uses lossless compression
• Actually the Bologna image is non of the above

Raster or Vector?
• Bologna image is svg (Scalable Vector Graphics)
• “Raster” is the pixel based image
– Rectangular grid of dots, each one a particular colour and
brightness
• “Vector” images build up image from library of shapes
– Better for designed images like logos
– Not good for photos with arbitrary information

Digital Images
• Digital Images didn’t have to happen
computer scientists
Chris Lilley Abraham Lempel

Insert it into the talk
• Copy and paste, drag and drop
• Metaphors from people working on a
desk
– Hence the name “desktop”
• GUI (graphical user interface)
– Key concepts like WYSIWIG
• (what you see is what you get)
• So standard I have to explain what it
used to be!

The way it used to be …
• Terminal with keyboard
• Do you see a mouse (or trackpad)?
• Multi users per computer
• This cost £000s
– And wasn’t a full computer!
• And couldn’t display graphics
– So you couldn’t see document in final form VT100 terminal

GUI
• GUI didn’t have to happen
computer scientists
Alan KayDoug Engelbart

I hope you see the point …
• There’s a LOT of layers
involved in finding out which
University is first, and
grabbing its image and putting
it in a presentation

I hope you see the point …
• Of course I have given you an
incredibly simplified version of
the story!

Programming
• I haven’t talked about programming …
• Which maybe you thought Computer Science
is all about
• It’s true that all these advances depended
critically on programming
• But Computer Science is not just about
learning programming languages
– Spanish degree is not just about learning Spanish
– English degree not just about learning English.

Programming Languages
• Another layer of abstraction between the
computer silicon and the programmer
• We don’t just have to write in 0s and 1s
• Each language has different goals
– Things it makes easier for the programmer
• Each language has disadvantages
– Things it is not so good at …
• Examples are
– Fortran, C, Cobol, Lisp, C++, Haskell, Idris…
• But there are one or two others as well

Programming Languages
• Programming Languages didn’t have to
happen
computer scientists
Grace Hopper (Admiral!)Ada Lovelace

Please tell me you get the point
the story!

Or I will have to talk about more
layers!
the story!

Computer Science in Action
• Most of the pictures you saw were old white
men
– Though they were much younger when they did
their key research
• Gender inequality a major problem for CS
– Perhaps the major problem for CS
• At St Andrews we try to do things about this
– In part by doing Computer Science!

• Karen Petrie
• Senior Lecturer in Computing at Dundee
• Computing graduate of St Andrews
• And inventor of the Petrie Multiplier
– (but not the namer of it!)
Images: Ian Gent
Petrie?

The Petrie Multiplier
• A thought experiment
• Let’s assume no gender difference in sexism
– Say 20% of people act like jerks to the opposite sex
– And 20% of CS people are women
• We will see amazing difference in result
• http://blog.ian.gent/2013/10/the-petrie-multiplier-why-
attack-on.html

Let’s start with
32 men.
In pink of course

Let’s start with
32 men.
In pink of course
The boy’s colour

“The generally accepted rule is pink
for the boys, and blue for the girls.
The reason is that pink, being a more
decided and stronger color, is more
suitable for the boy, while blue, which
is more delicate and dainty, is prettier
for the girl.”
-- Earnshaw's Infants' Department
1918

“The generally accepted rule is pink
for the boys, and blue for the girls.”
Something to remember next time
you catch yourself thinking some
gender difference is inherent

Now add 8
more men
who act like
jerks to women

And 2
more women
who act like
jerks to men

Remember!
Each gender is
equally jerky to
the other

Some man
acted like a
jerk to some
woman.
Not good.

Some woman
acted like a
jerk to some
man.
Also not good.

Unluckiest man of 40 does better than luckiest woman of 10!

• 0.35 bad experiences per man
• 5.6 bad experiences per woman
• 16x as many
• Ratio of bad experiences is square of
gender ratio
• 80% men : 20% women = 4 : 1

Petrie Multiplier:
Lessons
• With women underrepresented
– Women experience amazing disparity of sexism
• With no assumption that men are worse
• So attacks on sexism in CS...
• ... and statements that women get it worse than
men
• are not attacks on men

CS at St Andrews is a Great Choice
• Computer Science is great
• St Andrews is great
• The University is great
• Computer Science at St Andrews University is
great
• The dogfood is great

The dogfood is great ????
• “Eating your own dog food, also called
dogfooding, is a slang term used to reference
a scenario in which a company (usually, a
computer software company) uses its own
product to demonstrate the quality and
capabilities of the product.”
– Wikipedia
• Not just capabilities but ….
– If e.g. you are selling a word processor
– You should be using your own word processor!

Dogfood…
• Graham Kirby
• BSc St Andrews
• PhD St Andrews

Dogfood…
• Al Dearle
• BSc St Andrews
• PhD St Andrews

Dogfood…
• Ian Miguel
• BSc St Andrews

Dogfood…
• Ishbel Duncan
• BSc St Andrews

Dogfood…
• Alex Bain
• BSc St Andrews

Dogfood…
• Stuart Norcross
• BSc St Andrews
• PhD St Andrews

Dogfood…
• Jonathan Lewis
• PhD St Andrews

Dogfood…
• Tom Kelsey
• PhD St Andrews

Dogfood…
• Dharini
Balasubramaniam
• PhD St Andrews

Dogfood…
• Ruth Letham
• PhD St Andrews

St Andrews is Great
• Even if you don’t like golf
• Beautiful seaside location
• Most of Scotland fairly easy to access
• Golf + University means better shops and
entertainment than town this size should have
• And can be ridiculously photogenic…

St Andrews is Great
• My hot water bottle story …
• Many people come here and never leave
• People who don’t like St Andrews…
– … usually are ones who love big city life
– And we just can’t provide that

St Andrews University is great
• Founded 1413
• Culmination of 600th Anniversary in 2013
Honorary degrees to Tim Berners-Lee,
Hillary Clinton
• Papal bull reenactment
– Original papal bull given to us by an antipope
– But we don’t tell anyone that

“St Andrews' commitment to student welfare
and safety is reflected in our consistently low
drop out rate - at just over 1% it's the lowest in
Scotland and the lowest in the UK behind only
Oxford and Cambridge.”
http://www.st-andrews.ac.uk/parents/aboutstandrews/

Put another way (if your parents contribute to
your choice or funding of University)…
… your parents would send you to the place with
the least chance of seeing you again!

CS at St Andrews is Great
• Really close attention to quality teaching
• Outstanding level of equipment provision
• Focus on project work in every year
– Optional in subhonours
– Compulsory in honours
• Research leaders teaching at all levels

We’re Number One
• We’ve been ranked number one more than once
• But we don’t care about league tables
– Kind of sort of well I mean we don’t care but if you
happen to look then yeah we are way up at the top
and we don’t really believe in them but you know we
can’t stop you looking
• But we do care deeply about providing great
education
• Always looking at how to improve things
– And working with students to do so

A little bit of honesty
• Three years ago we were ranked much lower
in Student Satisfaction
• But since not much changed each year
– Though we did listen to feedback
– And improved in certain areas
• We deduce that …
• Computer Science in the UK is an incredibly
satisfying subject to study

Computer Science is Great!
• Computer Science is a great choice of degree
• And I’m somebody who did a Maths degree!
– Did do a Computer Science PhD though
• One reason (not the main one …)
– You can get to be Chief Scientific Advisor to the
Scottish Government

Chief Geek
• Muffy Calder
– PhD St Andrews
– Chief Scientific Adviser to the
Scottish Government
– Necklace spells out in ASCII
– “Chief Geek!”

A million digits of pi…
Photo: Ian Gent (or close relative)
My mother Ann Margaret Gent
A maths teacher

A woman of calculators
Photo: Ian Gent (or close relative)
4 bit calculator from
sister’s doll’s house base!
Curta Calculator TI-57 Programmable Calculator
imagesWikipedia

Photo: Amazon
“One Million” by Hendrik
Hertzberg
To show students just what a
million is like
200 pages, 5000 dots per
page, one million dots

She never found the book …
So once I found online a
million digits of pi and printed
them for her
As a present
And I found them on a
precursor of the web called
gopher

Midair cockpit swapper
Photo: LA(PHOT) Abbie Herron/MODPhoto: Ian Gent (or close relative)

An important piece of honesty
• Nobody has ever said…
• “My CS degree at St Andrews was easy”
• We do work you hard
– Maybe harder than any other degree at St A.
• Not something we’re proud of
• But fundamentally it’s hard work to learn CS
• And our students are still very satisfied

Why study Computer Science?
• It’s interesting
• It’s fun
• It’s important
• It’s creative
• It’s beautiful
• And it’s got lots and lots of layers!

Video Credit
• Why I love CS, by James Montgomery 2014
• https://www.ucas.com/corporate/news-and-key-
documents/love-learning-2014-competition-winners

Image Credits (1)
• Images not explicitly credited here are by one of University of St Andrews, Ian Gent, or family
of Ian Gent
• Bologna University Crest, Vectorized by User:Nandhp [Public domain], via Wikimedia
Commons
• “One Million Dots” book cover, photo from Amazon.com
• “Swordfish Aircraft” Photo: LA(PHOT) Abbie Herron/MOD [OGL
(http://www.nationalarchives.gov.uk/doc/open-government-licence/version/1/)], via
Wikimedia Commons
• “Curta calculator” By Larry McElhiney (Created this image in Indianapolis, IN) [CC BY-SA 2.5
(http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons
• “TI – 57 – France, mars 2006” by monster1000,
https://commons.wikimedia.org/wiki/File:TI_57-b.jpg
• “VT100”, By Jason Scott (Flickr: IMG_9976) [CC BY 2.0
(http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
• "Bitmap VS SVG" by Yug, modifications by 3247 - Unknown. Licensed under CC BY-SA 2.5 via
Wikimedia Commons -
https://commons.wikimedia.org/wiki/File:Bitmap_VS_SVG.svg#/media/File:Bitmap_VS_SVG.
svg

Image Credits (2)
• “Jon Postel sitting in office” by Carl Malamud
https://commons.wikimedia.org/wiki/File:Jon_Postel_sitting_in_office.jpg
• "Paul Mockapetris" by Jordiipa - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons -
https://commons.wikimedia.org/wiki/File:Paul_Mockapetris.JPG#/media/File:Paul_Mockapetris.JP
G
• “Ward Cunningham”, By Carrigg Photography for the Wikimedia Foundation (Own work) [CC BY-SA
3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
• Ada Lovelace, by Alfred Edward Chalon [Public domain], via Wikimedia Commons
• “Doug Engelbart” By Alex Handy from Oakland, Nmibia (Dr. Douglas C. Engelbart Uploaded by
Edward) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
• “Grace Hopper” By James S. Davis [Public domain], via Wikimedia Commons
• "Alan Kay (3097597186)" by Marcin Wichary from San Francisco, U.S.A. - Alan KayUploaded by
JoJan. Licensed under CC BY 2.0 via Wikimedia Commons -
https://commons.wikimedia.org/wiki/File:Alan_Kay_(3097597186).jpg#/media/File:Alan_Kay_(309
7597186).jpg
• “Tim Berners-Lee CP 2" by Silvio Tanaka - originally posted to Flickr as Tim Berners-Lee. Licensed
under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:Tim_Berners-
Lee_CP_2.jpg#/media/File:Tim_Berners-Lee_CP_2.jpg
• “Muffy Calder” By Miguel Nacenta (University of St Andrews) [CC BY-SA 3.0
• “Jimmy Wales” By Niccolò Caranti (Own work) [CC BY-SA 3.0

Image Credits (3)
• "Marc Andreessen" by Brian Solis - IMG_8642. Licensed under CC BY 2.0 via Wikimedia Commons -
https://commons.wikimedia.org/wiki/File:Marc_Andreessen.jpg#/media/File:Marc_Andreessen.jpg
• “Charles Goldfarb”, Charles F Goldfarb Press Kit, http://www.sgmlsource.com/press/
• “Ted Nelson” By Dgies (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL
(http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons
• “Vannevar Bush” OEM Defense, Public Domain,
• “Karen Sparck Jones”, University of Cambridge [CC BY 2.5 (http://creativecommons.org/licenses/by/2.5)],
via Wikimedia Commons
• “Sergey Brin” By Joi Ito [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia
Commons
• "Larry Page in the European Parliament, 17.06.2009" by Marcin Mycielski, European Parliament
(Stansfield) - Own work. Licensed under GFDL via Wikimedia Commons -
https://commons.wikimedia.org/wiki/File:Larry_Page_in_the_European_Parliament,_17.06.2009.jpg#/me
dia/File:Larry_Page_in_the_European_Parliament,_17.06.2009.jpg
• “Bob Kahn”, By Вени Марковски | Veni Markovski (Own work) [CC BY-SA 3.0
• Vint Cerf talking to Ian Gent, by Özgür Akgün,
https://twitter.com/ozgurakgun/status/613056047209648128/photo/1
• “Chris Lilley”, By Andy Fitzsimon (https://www.flickr.com/photos/andyfitz/2494476574) [CC BY-SA 2.0
• “Abraham Lempel” By Staelin (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0) or CC
BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

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