63   mistaken: in fact they are still an active research area. On the top of my head, I can give

    63   mistaken: in fact they are still an active research area. On the top of my head, I can give

    64   you at least ten research papers that appeared in the last few years.

    64   you at least ten research papers that appeared in the last few years.

    65   For example

    65   For example

    66   <A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/regex-parsing-derivatives.pdf">this paper</A> 

    66   <A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/regex-parsing-derivatives.pdf">this paper</A> 

    67   about regular expression matching and derivatives was presented in 2014 at the international 

    67   about regular expression matching and derivatives was presented in 2014 at the international 

    69   at the international ITP conference.

    69   at the international ITP conference.

    70   The task in this project is to implement these results and use them for lexing.</p>

    70   The task in this project is to implement these results and use them for lexing.</p>

    71 

    71 

    72   <p>The background for this project is that some regular expressions are 

    72   <p>The background for this project is that some regular expressions are 

    73   &ldquo;<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>&rdquo;

    73   &ldquo;<A HREF="http://en.wikipedia.org/wiki/ReDoS#Examples">evil</A>&rdquo;

   124   (for example subexpression matching, which my rainy-afternoon matcher cannot). I am sure they thought

   124   (for example subexpression matching, which my rainy-afternoon matcher cannot). I am sure they thought

   125   about the problem much longer than a single afternoon. The task 

   125   about the problem much longer than a single afternoon. The task 

   126   in this project is to find out how good they actually are by implementing the results from their paper. 

   126   in this project is to find out how good they actually are by implementing the results from their paper. 

   127   Their approach to regular expression matching is also based on the concept of derivatives.

   127   Their approach to regular expression matching is also based on the concept of derivatives.

   128   I used derivatives very successfully once for something completely different in a

   128   I used derivatives very successfully once for something completely different in a

   130   about the <A HREF="http://en.wikipedia.org/wiki/Myhill–Nerode_theorem">Myhill-Nerode theorem</A>.

   130   about the <A HREF="http://en.wikipedia.org/wiki/Myhill–Nerode_theorem">Myhill-Nerode theorem</A>.

   131   So I know they are worth their money. Still, it would be interesting to actually compare their results

   131   So I know they are worth their money. Still, it would be interesting to actually compare their results

   132   with my simple rainy-afternoon matcher and potentially “blow away” the regular expression matchers 

   132   with my simple rainy-afternoon matcher and potentially “blow away” the regular expression matchers 

   133   in Python, Ruby and Java (and possibly in Scala too). The application would be to implement a fast lexer for

   133   in Python, Ruby and Java (and possibly in Scala too). The application would be to implement a fast lexer for

   134   programming languages, or improve the network traffic analysers in the tools <A HREF="https://www.snort.org">Snort</A> and

   134   programming languages, or improve the network traffic analysers in the tools <A HREF="https://www.snort.org">Snort</A> and

   137 

   137 

   138   <p>

   138   <p>

   139   <B>Literature:</B> 

   139   <B>Literature:</B> 

   140   The place to start with this project is obviously this

   140   The place to start with this project is obviously this

   141   <A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/regex-parsing-derivatives.pdf">paper</A>

   141   <A HREF="http://www.home.hs-karlsruhe.de/~suma0002/publications/regex-parsing-derivatives.pdf">paper</A>

   143   Traditional methods for regular expression matching are explained

   143   Traditional methods for regular expression matching are explained

   144   in the Wikipedia articles 

   144   in the Wikipedia articles 

   145   <A HREF="http://en.wikipedia.org/wiki/DFA_minimization">here</A> and 

   145   <A HREF="http://en.wikipedia.org/wiki/DFA_minimization">here</A> and 

   146   <A HREF="http://en.wikipedia.org/wiki/Powerset_construction">here</A>.

   146   <A HREF="http://en.wikipedia.org/wiki/Powerset_construction">here</A>.

   147   The authoritative <A HREF="http://infolab.stanford.edu/~ullman/ialc.html">book</A>

   147   The authoritative <A HREF="http://infolab.stanford.edu/~ullman/ialc.html">book</A>

   432   heart rate and body temperature; the Raspberry Pi collects this data and makes it accessible via a simple

   432   heart rate and body temperature; the Raspberry Pi collects this data and makes it accessible via a simple

   433   web-service. The picture on the right is another project that implements an airmouse using an Arduino.

   433   web-service. The picture on the right is another project that implements an airmouse using an Arduino.

   434 

   434 

   435   <center>

   435   <center>

   436     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   436     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   438          alt="Raspberry Pi"

   438          alt="Raspberry Pi"

   439          width="209" height="313">

   439          width="209" height="313">

   440 

   440 

   441     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   441     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   443          alt="Raspberry Pi"

   443          alt="Raspberry Pi"

   444          width="450" height="254">

   444          width="450" height="254">

   445 

   445 

   446     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   446     <img style="-webkit-user-select: none; cursor: -webkit-zoom-in;"

   448          alt="Raspberry Pi"

   448          alt="Raspberry Pi"

   449          width="250" height="254">  

   449          width="250" height="254">  

   450   </center>

   450   </center>

   451  

   451  

   452 

   452 

   495  algorithm switched on and it almost caused a catastrophic mission failure (see

   495  algorithm switched on and it almost caused a catastrophic mission failure (see

   496  this youtube video <A HREF="http://www.youtube.com/watch?v=lyx7kARrGeM">here</A>

   496  this youtube video <A HREF="http://www.youtube.com/watch?v=lyx7kARrGeM">here</A>

   497  for an explanation what happened).

   497  for an explanation what happened).

   498  We were able to prove the correctness of this algorithm, but were also able to

   498  We were able to prove the correctness of this algorithm, but were also able to

   499  establish the correctness of some optimisations in this

   499  establish the correctness of some optimisations in this

   501  </p>

   501  </p>

   502 

   502 

   503  <p>On a much smaller scale, there are a few small programs and underlying algorithms where it

   503  <p>On a much smaller scale, there are a few small programs and underlying algorithms where it

   504  is not really understood whether they always compute a correct result (for example the

   504  is not really understood whether they always compute a correct result (for example the

   505  regular expression matcher by Sulzmann and Lu in project [CU1]). The aim of this

   505  regular expression matcher by Sulzmann and Lu in project [CU1]). The aim of this

   546 

   546 

   547 

   547 

   548 <li> <H4>Earlier Projects</H4>

   548 <li> <H4>Earlier Projects</H4>

   549 

   549 

   550  I am also open to project suggestions from you. You might find some inspiration from my earlier projects:

   550  I am also open to project suggestions from you. You might find some inspiration from my earlier projects:

   562 </ul>

   562 </ul>

   563 </TD>

   563 </TD>

   564 </TR>  

   564 </TR>  

   565 </TABLE>

   565 </TABLE>

   566         

   566