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<H2>2013/14 BSc Projects</H2>+ −
<H4>Supervisor: Christian Urban</H4> + −
<H4>Email: christian dot urban at kcl dot ac dot uk, Office: Strand Building S1.27</H4>+ −
<H4>If you are interested in a project, please send me an email and we can discuss details. Please include+ −
a short description about your programming skills and Computer Science background in your first email. + −
I will also need your King's username in order to book the project for you. Thanks.</H4> + −
+ −
<H4>Note that besides being a lecturer at the theoretical end of Computer Science, I am also a passionate+ −
<A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker</A> …+ −
defined as “a person who enjoys exploring the details of programmable systems and + −
stretching their capabilities, as opposed to most users, who prefer to learn only the minimum + −
necessary.” I am always happy to supervise like-minded students.</H4> + −
+ −
<ul class="striped">+ −
<li> <H4>[CU1] Regular Expression Matching and Partial Derivatives</H4>+ −
+ −
<p>+ −
<B>Description:</b> + −
<A HREF="http://en.wikipedia.org/wiki/Regular_expression">Regular expressions</A> + −
are extremely useful for many text-processing tasks such as finding patterns in texts,+ −
lexing programs, syntax highlighting and so on. Given that regular expressions were+ −
introduced in 1950 by <A HREF="http://en.wikipedia.org/wiki/Stephen_Cole_Kleene">Stephen Kleene</A>,+ −
you might think regular expressions have since been studied and implemented to death. But you would definitely be+ −
mistaken: in fact they are still an active research area. For example+ −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">this paper</A> + −
about regular expression matching and partial derivatives was presented last summer at the international + −
PPDP'12 conference. They even work on a followup paper that has not yet been presented at any+ −
conference. The task in this project is to implement their results.</p>+ −
+ −
<p>The background for this project is that some regular expressions are + −
“<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>”+ −
and can “stab you in the back” according to+ −
this <A HREF="http://tech.blog.cueup.com/regular-expressions-will-stab-you-in-the-back">blog post</A>.+ −
For example, if you use in <A HREF="http://www.python.org">Python</A> or + −
in <A HREF="http://www.ruby-lang.org/en/">Ruby</A> (probably also other mainstream programming languages) the + −
innocently looking regular expression <code>a?{28}a{28}</code> and match it, say, against the string + −
<code>aaaaaaaaaaaaaaaaaaaaaaaaaaaa</code> (that is 28 <code>a</code>s), you will soon notice that your CPU usage goes to 100%. In fact,+ −
Python and Ruby need approximately 30 seconds of hard work for matching this string. You can try it for yourself:+ −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/progs/re.py">re.py</A> (Python version) and + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/progs/re.rb">re.rb</A> + −
(Ruby version). You can imagine an attacker+ −
mounting a nice <A HREF="http://en.wikipedia.org/wiki/Denial-of-service_attack">DoS attack</A> against + −
your program if it contains such an “evil” regular expression. Actually + −
<A HREF="http://www.scala-lang.org/">Scala</A> (and also Java) are almost immune from such+ −
attacks as they can deal with strings of up to 4,300 <code>a</code>s in less than a second. But if you scale+ −
the regular expression and string further to, say, 4,600 <code>a</code>s, then you get a <code>StackOverflowError</code> + −
potentially crashing your program.+ −
</p>+ −
+ −
<p>+ −
On a rainy afternoon, I implemented + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/cgi-bin/repos.cgi/afl-material/raw-file/tip/progs/re3.scala">this</A> + −
regular expression matcher in Scala. It is not as fast as the official one in Scala, but+ −
it can match up to 11,000 <code>a</code>s in less than 5 seconds without raising any exception+ −
(remember Python and Ruby both need nearly 30 seconds to process 28(!) <code>a</code>s, and Scala's+ −
official matcher maxes out at 4,600 <code>a</code>s). My matcher is approximately+ −
85 lines of code and based on the concept of + −
<A HREF="http://lambda-the-ultimate.org/node/2293">derivatives of regular expressions</A>.+ −
These derivatives were introduced in 1964 by <A HREF="http://en.wikipedia.org/wiki/Janusz_Brzozowski_(computer_scientist)">+ −
Janusz Brzozowski</A>, but according to this + −
<A HREF="http://www.cl.cam.ac.uk/~so294/documents/jfp09.pdf">paper</A> had been lost in the “sands of time”.+ −
The advantage of derivatives is that they side-step completely the usual + −
<A HREF="http://hackingoff.com/compilers/regular-expression-to-nfa-dfa">translations</A> of regular expressions+ −
into NFAs or DFAs, which can introduce the exponential behaviour exhibited by the regular+ −
expression matchers in Python and Ruby.+ −
</p>+ −
+ −
<p>+ −
Now the authors from the + −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">PPDP'12-paper</A> mentioned + −
above claim they are even faster than me and can deal with even more features of regular expressions+ −
(for example subexpression matching, which my rainy-afternoon matcher cannot). I am sure they thought+ −
about the problem much longer than a single afternoon. The task + −
in this project is to find out how good they actually are by implementing the results from their paper. + −
Their approach is based on the concept of partial derivatives introduced in 1994 by+ −
<A HREF="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.56.2509&rep=rep1&type=pdf">Valentin Antimirov</A>.+ −
I used them once myself in a <A HREF="http://www.inf.kcl.ac.uk/staff/urbanc/Publications/rexp.pdf">paper</A> + −
in order to prove the <A HREF="http://en.wikipedia.org/wiki/Myhill–Nerode_theorem">Myhill-Nerode theorem</A>.+ −
So I know they are worth their money. Still, it would be interesting to actually compare their results+ −
with my simple rainy-afternoon matcher and potentially “blow away” the regular expression matchers + −
in Python and Ruby (and possibly in Scala too).+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The place to start with this project is obviously this+ −
<A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/ppdp12-part-deriv-sub-match.pdf">paper</A>.+ −
Traditional methods for regular expression matching are explained+ −
in the Wikipedia articles + −
<A HREF="http://en.wikipedia.org/wiki/DFA_minimization">here</A> and + −
<A HREF="http://en.wikipedia.org/wiki/Powerset_construction">here</A>.+ −
The authoritative <A HREF="http://infolab.stanford.edu/~ullman/ialc.html">book</A>+ −
on automata and regular expressions is by John Hopcroft and Jeffrey Ullmann (available in the library). + −
There is also an online course about this topic by Ullman at + −
<A HREF="https://www.coursera.org/course/automata">Coursera</A>, though IMHO not + −
done with love. + −
Finally, there are millions of other pointers about regular expression+ −
matching on the Web. I found the chapter on Lexing in this+ −
<A HREF="http://www.diku.dk/~torbenm/Basics/">online book</A> very helpful.+ −
Test cases for “<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>”+ −
regular expressions can be obtained from <A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">here</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with an interest in theory and some+ −
reasonable programming skills. The project can be easily implemented+ −
in functional languages like+ −
<A HREF="http://www.scala-lang.org/">Scala</A>,+ −
F#, + −
<A HREF="http://en.wikipedia.org/wiki/Standard_ML">ML</A>, + −
<A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>, etc. Python and other non-functional languages+ −
can be also used, but seem much less convenient.+ −
</p>+ −
+ −
<li> <H4>[CU2] Machine Code Generation for a Simple Compiler</H4>+ −
+ −
<p>+ −
<b>Description:</b> + −
Compilers translate high-level programs that humans can read and write into+ −
efficient machine code that can be run on a CPU or virtual machine.+ −
A compiler for a simple functional language generating X86 code is described+ −
<A HREF="https://github.com/chameco/Shade">here</A>.+ −
I recently implemented a very simple compiler for an even simpler functional+ −
programming language following this + −
<A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-toplas.pdf">paper</A> + −
(also described <A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-tr.pdf">here</A>).+ −
My code, written in <A HREF="http://www.scala-lang.org/">Scala</A>, of this compiler is + −
<A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/compiler.scala">here</A>.+ −
The compiler can deal with simple programs involving natural numbers, such+ −
as Fibonacci numbers or factorial (but it can be easily extended - that is not the point).+ −
</p>+ −
+ −
<p>+ −
While the hard work has been done (understanding the two papers above),+ −
my compiler only produces some idealised machine code. For example I+ −
assume there are infinitely many registers. The goal of this+ −
project is to generate machine code that is more realistic and can+ −
run on a CPU, like X86, or run on a virtual machine, say the JVM. + −
This gives probably a speedup of thousand times in comparison to+ −
my naive machine code and virtual machine. The project+ −
requires to dig into the literature about real CPUs and generating + −
real machine code. + −
</p>+ −
+ −
<p>+ −
<B>Literature:</B>+ −
There is a lot of literature about compilers + −
(for example <A HREF="http://www.cs.princeton.edu/~appel/papers/cwc.html">this book</A> -+ −
I can lend you my copy for the duration of the project, or this+ −
<A HREF="http://www.diku.dk/~torbenm/Basics/">online book</A>). A very good overview article+ −
about implementing compilers by + −
<A HREF="http://tratt.net/laurie/">Laurie Tratt</A> is + −
<A HREF="http://tratt.net/laurie/tech_articles/articles/how_difficult_is_it_to_write_a_compiler">here</A>.+ −
An online book about the Art of Assembly Language is+ −
<A HREF="http://flint.cs.yale.edu/cs422/doc/art-of-asm/pdf/">here</A>.+ −
An introduction into x86 machine code is <A HREF="http://ianseyler.github.com/easy_x86-64/">here</A>.+ −
Intel's official manual for the x86 instruction is + −
<A HREF="http://download.intel.com/design/intarch/manuals/24319101.pdf">here</A>. + −
A simple assembler for the JVM is described <A HREF="http://jasmin.sourceforge.net">here</A>.+ −
An interesting twist of this project is to not generate code for a CPU, but+ −
for the intermediate language of the <A HREF="http://llvm.org">LLVM</A> compiler+ −
(also described <A HREF="https://wiki.aalto.fi/display/t1065450/LLVM+IR">here</A> and+ −
<A HREF="http://llvm.org/docs/LangRef.html">here</A>). If you want to see+ −
what machine code looks like you can compile your C-program using gcc -S.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project for a student with a deep interest in programming languages and+ −
compilers. Since my compiler is implemented in <A HREF="http://www.scala-lang.org/">Scala</A>,+ −
it would make sense to continue this project in this language. I can be+ −
of help with questions and books about <A HREF="http://www.scala-lang.org/">Scala</A>.+ −
But if Scala is a problem, my code can also be translated quickly into any other functional+ −
language. + −
</p>+ −
+ −
<p>+ −
<B>PS:</B> Compiler projects, like [CU2] and [CU3], consistently get high marks.+ −
I suprvised four so far and none of them got below 70% - one even was awarded a prize.+ −
</p>+ −
+ −
<li> <H4>[CU3] Language Translator into JavaScript</H4>+ −
+ −
<p>+ −
<b>Description:</b> + −
<A HREF="http://www.w3schools.com/js/">JavaScript</A> is a language that is supported by most+ −
browsers and therefore is a favourite+ −
vehicle for Web-programming. Some call it <B>the</B> scripting language of the Web.+ −
Unfortunately, JavaScript is probably one of the worst+ −
languages to program in (being designed and released in a hurry). <B>But</B> it can be used as a convenient target+ −
for translating programs from other languages. In particular there are two+ −
very optimised subsets of JavaScript that can be used for this purpose:+ −
one is <A HREF="http://asmjs.org">asm.js</A> and the other is+ −
<A HREF="https://github.com/kripken/emscripten/wiki">emscripten</A>.+ −
There is a <A HREF="https://github.com/kripken/emscripten/wiki/Tutorial">tutorial</A> for emscripten+ −
and an impressive <A HREF="http://www.unrealengine.com/html5/">demo</A> which runs the+ −
<A HREF="http://en.wikipedia.org/wiki/Unreal_Engine">Unreal Engine 3</A>+ −
in a browser with spectacular speed. This was achieved by compiling the+ −
C-code of the Unreal Engine to the LLVM intermediate language and then translating the LLVM+ −
code to JavaScript.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This project is about exploring these two subsets of JavaScript and implement a translator+ −
of a small language into them. This is similar to the project [CU2] above and requires+ −
similar skills. In addition it would be good to have already some familiarity with JavaScript.+ −
There are plenty of <A HREF="http://www.w3schools.com/js/">tutorials</A> on the Web.+ −
<A HREF="http://jsbooks.revolunet.com">Here</A> is a list of free books on JavaScript.+ −
This is a project for a student who wants to get more familiar with JavaScript and Web-programming.+ −
A project from which you can draw inspiration is this+ −
<A HREF="http://jlongster.com/2012/01/04/outlet-my-lisp-to-javascript-experiment.html">List-to-JavaScript</A>+ −
translator. <A HREF="https://bitbucket.org/ktg/parenjs/overview">Here</A> is another such project.+ −
And <A HREF="https://github.com/viclib/liscript">another</A> in less than 100 lines of code.+ −
<A HREF="http://en.wikipedia.org/wiki/CoffeeScript">Coffeescript</A> is a similar project+ −
except that it is already quite <A HREF="http://coffeescript.org">mature</A>. And finally not to+ −
forget <A HREF="http://www.typescriptlang.org">TypeScript</A> developed by Microsoft. The main+ −
difference between these projects and this one is that they translate into relatively high-level+ −
JavaScript code; none of them use the much lower levels <A HREF="http://asmjs.org">asm.js</A> and + −
<A HREF="https://github.com/kripken/emscripten/wiki">emscripten</A>.+ −
</p>+ −
+ −
<li> <H4>[CU4] Slide-Making in the Web-Age</H4>+ −
+ −
<p>+ −
The standard technology for writing scientific papers in Computer Science is to use+ −
<A HREF="http://en.wikipedia.org/wiki/LaTeX">LaTeX</A>, a document preparation+ −
system originally implemented by <A HREF="http://en.wikipedia.org/wiki/Donald_Knuth">Donald Knuth</A>+ −
and <A HREF="http://en.wikipedia.org/wiki/Leslie_Lamport">Leslie Lamport</A>.+ −
LaTeX produces very pleasantly looking documents, can deal nicely with mathematical+ −
formulas and is very flexible. If you are interested, <A HREF="http://openwetware.org/wiki/Word_vs._LaTeX">here</A>+ −
is a side-by-side comparison between Word and LaTeX (which LaTeX “wins” with 18 out of 21 points).+ −
Computer scientists not only use LaTeX for documents,+ −
but also for slides (really, nobody who wants to be cool uses Keynote or Powerpoint).+ −
</p>+ −
+ −
<p>+ −
Although used widely, LaTeX seems nowadays a bit dated for producing+ −
slides. Unlike documents, which are typically “static” and published in a book or journal,+ −
slides often contain changing contents that might first only be partially visible and+ −
only later be revealed as the “story” of a talk or lecture demands.+ −
Also slides often contain animated algorithms where each state in the+ −
calculation is best explained by highlighting the changing data.+ −
</p>+ −
+ −
<p>+ −
It seems HTML and JavaScript are much better suited for generating+ −
such animated slides. This <A HREF="http://www.impressivewebs.com/html-slidedeck-toolkits/">page</A>+ −
links to 22 slide-generating programs using this combination of technologies. + −
<A HREF="http://www.impressivewebs.com/html-slidedeck-toolkits/">Here</A> are even more such+ −
projects. However, the problem with all of these project is that they depend heavily on the users being+ −
able to write JavaScript, CCS or HTML...not something one would like to depend on given that+ −
“normal” users likely only have a LaTeX background. The aim of this project is to invent a+ −
very simple language that is inspired by LaTeX and then generate from code written in this language+ −
slides that can be displayed in a web-browser.+ −
</p>+ −
+ −
<p>+ −
This sounds complicated, but there is already some help available:+ −
<A HREF="http://www.mathjax.org">Mathjax</A> is a JavaScript library that can+ −
be used to display mathematical text, for example+ −
+ −
<blockquote>+ −
<p>When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are+ −
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\).</p>+ −
</blockquote>+ −
+ −
by writing code in the familiar LaTeX-way. This can be reused. There are also plenty of JavaScript+ −
libraries for graphical animations (for example+ −
<A HREF="http://raphaeljs.com">Raphael</A>,+ −
<A HREF="http://svgjs.com">SVG.JS</A>,+ −
<A HREF="http://bonsaijs.org">Bonsaijs</A>,+ −
<A HREF="http://jsxgraph.uni-bayreuth.de/wp/">JSXGraph</A>). The inspiration for how the user should be able to write+ −
slides could come from the LaTeX packages <A HREF="http://en.wikipedia.org/wiki/Beamer_(LaTeX)">Beamer</A>+ −
and <A HREF="http://en.wikipedia.org/wiki/PGF/TikZ">PGF/TikZ</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This is a project requires good knowledge of JavaScript. You need to be able to+ −
parse a language and translate it to a suitable part of JavaScript using+ −
appropriate libraries. Tutorials for JavaScript are <A HREF="http://www.w3schools.com/js/">here</A>.+ −
A parser generator for JavaScript is <A HREF="http://pegjs.majda.cz">here</A>. There are probably also+ −
others.+ −
</p>+ −
+ −
<li> <H4>[CU5] An Online Student Voting System</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
One of the more annoying aspects of giving a lecture is to ask a question+ −
to the students and no matter how easy the question is to not + −
receive any answer. Recently, the online course system + −
<A HREF="http://www.udacity.com">Udacity</A> made an art out of+ −
asking questions during lectures (see for example the+ −
<A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A> + −
course CS253).+ −
The lecturer there gives multiple-choice questions as part of the lecture and the students need to + −
click on the appropriate answer. This works very well in the online world. + −
For “real-world” lectures, the department has some + −
<A HREF="http://en.wikipedia.org/wiki/Audience_response">clickers</A>+ −
(these are little devices which form a part of an audience response systems). However, + −
they are a logistic nightmare for the lecturer: they need to be distributed + −
during the lecture and collected at the end. Nowadays, where students+ −
come with their own laptop or smartphone to lectures, this can+ −
be improved.+ −
</p>+ −
+ −
<p>+ −
The task of this project is to implement an online student+ −
polling system. The lecturer should be able to prepare + −
questions beforehand (encoded as some web-form) and be able to + −
show them during the lecture. The students+ −
can give their answers by clicking on the corresponding webpage.+ −
The lecturer can then collect the responses online and evaluate them + −
immediately. Such a system is sometimes called+ −
<A HREF="http://en.wikipedia.org/wiki/Audience_response#Smartphone_.2F_HTTP_voting">HTML voting</A>. + −
There are a number of commercial+ −
solutions for this problem, but they are not easy to use (in addition+ −
to being ridiculously expensive). A good student can easily improve upon+ −
what they provide. + −
</p>+ −
+ −
<p>+ −
The problem of student polling is not as hard as + −
<A HREF="http://en.wikipedia.org/wiki/Electronic_voting">electronic voting</A>, + −
which essentially is still an unsolved problem in Computer Science. The+ −
students only need to be prevented from answering question more than once thus skewing+ −
any statistics. Unlike electronic voting, no audit trail needs to be kept+ −
for student polling. Restricting the number of answers can probably be solved + −
by setting appropriate cookies on the students+ −
computers or smart phones.+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
The project requires fluency in a web-programming language (for example + −
<A HREF="http://en.wikipedia.org/wiki/JavaScript">Javascript</A>,+ −
<A HREF="http://en.wikipedia.org/wiki/Go_(programming_language)">Go</A>, + −
<A HREF="http://www.scala-lang.org/">Scala</A>). However JavaScript with+ −
the <A HREF="http://nodejs.org">Node.js</A> extension seems to be best suited for the job.+ −
<A HREF="http://www.nodebeginner.org">Here</A> is a tutorial on Node.js for beginners.+ −
For web-programming the + −
<A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A>+ −
course at <A HREF="http://www.udacity.com">Udacity</A> is a good starting point + −
to be aware of the issues involved. This course uses <A HREF="http://www.python.org">Python</A>.+ −
To evaluate the answers from the students, Google's + −
<A HREF="https://developers.google.com/chart/image/docs/making_charts">Chart Tools</A>+ −
might be useful, which are also described in this + −
<A HREF="http://www.youtube.com/watch?v=NZtgT4jgnE8">youtube</A> video.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
In order to provide convenience for the lecturer, this project needs very good web-programming skills. A + −
<A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker mentality</A>+ −
(see above) is probably very beneficial: web-programming is an area that only emerged recently and+ −
many tools still lack maturity. You probably have to experiment a lot with several different+ −
languages and tools.+ −
</p>+ −
+ −
<li> <H4>[CU6] An Infrastructure for Displaying and Animating Code in a Web-Browser</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
The project aim is to implement an infrastructure for displaying and+ −
animating code in a web-browser. The infrastructure should be agnostic+ −
with respect to the programming language, but should be configurable.+ −
I envisage something smaller than the projects + −
<A HREF="http://www.pythontutor.com">here</A> (for Python),+ −
<A HREF="http://ideone.com">here</A> (for Java),+ −
<A HREF="http://codepad.org">here</A> (for multiple languages),+ −
<A HREF="http://www.w3schools.com/html/tryit.asp?filename=tryhtml_intro">here</A> (for HTML)+ −
<A HREF="http://repl.it/languages/JavaScript">here</A> (for JavaScript),+ −
and <A HREF="http://www.scala-tour.com/#/welcome">here</A> (for Scala).+ −
</p>+ −
+ −
<p>+ −
The tasks in this project are being able (1) to lex and parse languages and (2) to write an interpreter.+ −
The goal is to implement this as much as possible in a language-agnostic fashion.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
Good skill in lexing and language parsing, as well as being fluent with web programming (for+ −
example JavaScript).+ −
</p>+ −
+ −
+ −
<li> <H4>[CU7] Implementation of a Distributed Clock-Synchronisation Algorithm developed at NASA</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
There are many algorithms for synchronising clocks. This+ −
<A HREF="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120000054_2011025573.pdf">paper</A> + −
describes a new algorithm for clocks that communicate by exchanging+ −
messages and thereby reach a state in which (within some bound) all clocks are synchronised.+ −
A slightly longer and more detailed paper about the algorithm is + −
<A HREF="http://hdl.handle.net/2060/20110020812">here</A>.+ −
The point of this project is to implement this algorithm and simulate networks of clocks.+ −
</p>+ −
+ −
<p>+ −
<B>Literature:</B> + −
There is a wide range of literature on clock synchronisation algorithms. + −
Some pointers are given in this+ −
<A HREF="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120000054_2011025573.pdf">paper</A>,+ −
which describes the algorithm to be implemented in this project. Pointers+ −
are given also <A HREF="http://en.wikipedia.org/wiki/Clock_synchronization">here</A>.+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
In order to implement a simulation of a network of clocks, you need to tackle+ −
concurrency. You can do this for example in the programming language+ −
<A HREF="http://www.scala-lang.org/">Scala</A> with the help of the + −
<A HREF="http://akka.io">Akka</a> library. This library enables you to send messages+ −
between different <I>actors</I>. <A HREF="http://www.scala-lang.org/node/242">Here</A> + −
are some examples that explain how to implement exchanging messages between actors. + −
</p>+ −
+ −
+ −
+ −
+ −
<li> <H4>[CU8] Raspberry Pi's and Arduinos</H4>+ −
+ −
<p>+ −
<B>Description:</B>+ −
This project is for true hackers! <A HREF="http://en.wikipedia.org/wiki/Raspberry_Pi">Raspberry Pi's</A>+ −
are small Linux computers the size of a credit-card and only cost £34 (see picture left below). They were introduced+ −
in 2012 and people went crazy...well some of them. There is a+ −
<A HREF="https://plus.google.com/communities/113390432655174294208?hl=en">Google+</A> community about Raspberry Pi's that has more+ −
than 58k of followers. It is hard to keep up with what people do with these small computers. The possibilities+ −
seem to be limitless. The main resource for Raspberry Pi's is <A HREF="http://www.raspberrypi.org">here</A>.+ −
There are <A HREF="http://www.themagpi.com">magazines</A> dedicated to them and tons of+ −
<A HREF="http://www.raspberrypi.org/phpBB3/viewforum.php?f=39">books</A> (not to mention+ −
floods of <A HREF="https://www.google.co.uk/search?q=raspberry+pi">online</A> material).+ −
Google just released a+ −
<A HREF="http://googlecreativelab.github.io/coder/">framework</A>+ −
for web-programming and for turning Raspberry Pi's into webservers.+ −
</p>+ −
+ −
<p>+ −
<A HREF="http://en.wikipedia.org/wiki/Arduino">Arduinos</A> are slightly older (from 2005) but still very cool (see picture right below). They+ −
are small single-board micro-controllers that can talk to various external gadgets (sensors, motors, etc). Since Arduinos+ −
are open-software and open-hardware there are many clones and add-on boards. Like for the Raspberry Pi, there+ −
is a lot of material <A HREF="https://www.google.co.uk/search?q=arduino">available</A> about Arduinos.+ −
The main reference is <A HREF="http://www.arduino.cc">here</A>. Like the Raspberry Pi's, the good thing about+ −
Arduinos is that they can be powered with simple AA-batteries.+ −
</p>+ −
+ −
<p>+ −
I have two such Raspberry Pi's including wifi-connectors and two <A HREF="http://www.raspberrypi.org/camera">cameras<A>.+ −
I also have two <A HREF="http://www.freaklabs.org/index.php/Blog/Store/Introducing-the-Freakduino-Chibi-An-Arduino-based-Board-For-Wireless-Sensor-Networking.html">Freakduino Boards</A> that are Arduinos extended with wireless communication. I can lend them to responsible+ −
students for one or two projects. However, the aim is to first come up with an idea for a project. Popular projects are+ −
automated temperature sensors, network servers, robots, web-cams (<A HREF="http://www.secretbatcave.co.uk/electronics/shard-rain-cam/">here</A>+ −
is a <A HREF="http://www.raspberrypi.org/archives/3547">web-cam</A> directed at the Shard that can+ −
<A HREF="http://www.secretbatcave.co.uk/software/shard-rain-cam-quantifying-cloudy/">tell</A>+ −
you whether it is raining or cloudy). There are plenty more ideas listed+ −
<A HREF="http://www.raspberrypi.org/phpBB3/viewforum.php?f=15">here</A> for Raspberry Pi's and+ −
<A HREF="http://playground.arduino.cc/projects/ideas">here</A> for Arduinos.+ −
</p>+ −
+ −
<p>+ −
There are essentially two kinds of projects: One is purely software-based. Software projects for Raspberry Pi's are often+ −
written in <A HREF="http://www.python.org">Python</A>, but since these are Linux-capable computers any other+ −
language would do as well. You can also write your own operating system as done+ −
<A HREF="http://www.cl.cam.ac.uk/projects/raspberrypi/tutorials/os/">here</A>. For example the students+ −
<A HREF="http://www.recantha.co.uk/blog/?p=4918">here</A> developed their own bare-metal OS and then implemented+ −
a chess-program on top of it (have a look at their very impressive+ −
<A HREF="http://www.youtube.com/watch?v=-03bouPsfEQ&feature=player_embedded">youtube</A> video).+ −
The other kind of project is a combination of hardware and software; usually attaching some sensors+ −
or motors to the Raspberry Pi or Arduino. This might require some soldering or what is called+ −
a <A HREF="http://en.wikipedia.org/wiki/Breadboard">bread-board</A>. But be careful before choosing a project+ −
involving new hardware: these devices+ −
can be destroyed (if “Vin connected to GND” or “drawing more than 30mA from a GPIO”+ −
does not make sense to you, you should probably stay away from such a project). + −
</p>+ −
+ −
<p>+ −
<center>+ −
<img style="-webkit-user-select: none; cursor: -webkit-zoom-in;+ −
"src="http://upload.wikimedia.org/wikipedia/commons/3/3d/RaspberryPi.jpg" width="313" height="209">+ −
+ −
<img style="-webkit-user-select: none; cursor: -webkit-zoom-in;+ −
"src="http://upload.wikimedia.org/wikipedia/commons/3/38/Arduino_Uno_-_R3.jpg" width="240" height="209">+ −
</center>+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
Well, you must be a hacker; happy to make things.+ −
</p>+ −
+ −
<li> <H4>[CU9] Online Collaboration System</H4>+ −
+ −
+ −
<li> <H4>[CU10] Proving Programs to be Correct</H4>+ −
+ −
<p>+ −
I am one of the main developers of the interactive theorem prover+ −
<A HREF="http://isabelle.in.tum.de">Isabelle</A>. This theorem prover+ −
has been used to establish the correctness of some quite large+ −
programs (for example an <A HREF="http://ertos.nicta.com.au/research/l4.verified/">operating system</A>).+ −
Together with colleagues from Nanjing, I used this theorem prover to establish the correctness of a+ −
scheduling algorithm, called+ −
<A HREF="http://en.wikipedia.org/wiki/Priority_inheritance">Priority Inheritance</A>,+ −
for real time operating systems. This scheduling algorithm is part of the operating+ −
system that drives, for example, the + −
<A HREF="http://en.wikipedia.org/wiki/Mars_Exploration_Rover">Mars rovers</A>.+ −
Actually, the very first Mars rover mission in 1997 did not have this+ −
algorithm switched on and it almost caused a catastrophic mission failure (see+ −
this youtube video <A HREF="http://www.youtube.com/watch?v=lyx7kARrGeM">here</A>+ −
for an explanation what happened).+ −
We were able to prove the correctness of this algorithm, but were also able to+ −
establish the correctness of some optimisations in this+ −
<A HREF="http://www.inf.kcl.ac.uk/staff/urbanc/Publications/pip.pdf">paper</A>.+ −
</p>+ −
+ −
<p>On a much smaller scale, there are a few small programs and underlying algorithms where it+ −
is not really understood whether they always compute a correct result (for example the+ −
regular expression matcher by Sulzmann and Lu in project [CU1]). The aim of this+ −
project is to completely specify an algorithm in Isabelle and then prove it correct (that is,+ −
it always computes the correct result).+ −
</p>+ −
+ −
<p>+ −
<B>Skills:</B> + −
This project is for a very good student with a knack for theory and formal reasoning.+ −
</p>+ −
+ −
<li> <H4>Earlier Projects</H4>+ −
+ −
I am also open to project suggestions from you. You might find some inspiration from my earlier projects:+ −
<A HREF="http://www.inf.kcl.ac.uk/staff/urbanc/bsc-projects-12.html">BSc 2012/13</A>, + −
<A HREF="http://www.inf.kcl.ac.uk/staff/urbanc/msc-projects-12.html">MSc 2012/13</A> + −
+ −
</ul>+ −
</TD>+ −
</TR>+ −
</TABLE>+ −
+ −
<P>+ −
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