2
+ − 1 <?xml version="1.0" encoding="utf-8"?>
+ − 2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+ − 3 <HEAD>
+ − 4 <TITLE>Homepage of Christian Urban</TITLE>
3
+ − 5 <BASE HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/">
2
+ − 6 </HEAD>
+ − 7
+ − 8 <BODY TEXT="#000000"
+ − 9 BGCOLOR="#4169E1"
+ − 10 LINK="#0000EF"
+ − 11 VLINK="#51188E"
+ − 12 ALINK="#FF0000">
+ − 13
+ − 14 <TABLE WIDTH="100%"
+ − 15 BGCOLOR="#4169E1"
+ − 16 BORDER="0"
+ − 17 FRAME="border"
+ − 18 CELLPADDING="10"
+ − 19 CELLSPACING="2"
+ − 20 RULES="all">
+ − 21
+ − 22 <!-- left column -->
+ − 23 <TR>
+ − 24 <TD BGCOLOR="#FFFFFF"
+ − 25 WIDTH="24%"
+ − 26 VALIGN="TOP"
+ − 27 ROWSPAN="8">
+ − 28
+ − 29 <B>Links</B><BR>
3
+ − 30 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/index.html">Home</A><BR>
+ − 31 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/publications.html">Publications</A><BR>
+ − 32 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/teaching.html">Teaching</A><BR>
+ − 33 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/travelling.html">Recent Talks</A><BR>
2
+ − 34 <A HREF="http://isabelle.in.tum.de/nominal/">My Research Group</A>
+ − 35 <BR>
+ − 36 <BR>
+ − 37
+ − 38 <B>Handy Information</B><BR>
3
+ − 39 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/logic.html">People in Logic</A><BR>
+ − 40 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/programming.html">Programming Languages</A><BR>
+ − 41 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/misc.html">Miscellaneous</A>
2
+ − 42 <BR><BR>
+ − 43
+ − 44 <A HREF="http://isabelle.in.tum.de/nominal/">
5
+ − 45 <IMG SRC="nominal-logo.gif" ALT="" style="border-width: 0px;" align="left"></A>
2
+ − 46 </TD>
+ − 47
+ − 48
+ − 49
+ − 50 <!-- right column -->
+ − 51 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 52 <A NAME="Home"></A>
+ − 53 <TABLE>
+ − 54 <TR>
+ − 55 <TD WIDTH="75%">
+ − 56 <H1>Christian Urban </H1>
+ − 57
+ − 58 <B>E-mail</B>
+ − 59 urbanc <I>at</I> in tum de<BR>
+ − 60 <BR>
+ − 61
+ − 62 <B>Address</B>
+ − 63 <A HREF="http://www.in.tum.de/en.html">Institute for Computer Science</A>
+ − 64 at the TU Munich (IV), Boltzmannstrasse 3, D-85748 Garching, Germany.
+ − 65 <BR><BR>
+ − 66
+ − 67 <B>Fax</B> +49 89 289 17307
+ − 68 </TD>
+ − 69 <TD align="right" valign="top">
3
+ − 70 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/picture-small.jpg"><IMG ALT="" SRC="picture-small.jpg" align="top"></A>
2
+ − 71 </TD>
+ − 72 </TR>
+ − 73 </TABLE>
+ − 74 <p>
+ − 75 <IMG SRC="new.gif" ALT="" style="" align="left"><A HREF="http://isabelle.in.tum.de/nominal/activities/idp" target="_top">Isabelle Documentation Project</A> (contains now a draft of a 200-page tutorial on Isabelle programming)<BR>
+ − 76 </TD>
+ − 77 </TR>
+ − 78
+ − 79 <TR>
+ − 80 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 81 <B>Current Position</B>
+ − 82 I have been awarded an
+ − 83 <A HREF="http://en.wikipedia.org/wiki/Emmy_Noether">Emmy-Noether</A>
+ − 84 <A HREF="http://www.dfg.de/en/research_funding/programmes/individual/emmy_noether/in_brief/index.html">fellowship</A>
+ − 85 to head an independent <A HREF="http://isabelle.in.tum.de/nominal/">research group</A> in
+ − 86 the Computer Science Department at the
+ − 87 <A HREF="http://www.in.tum.de/en.html">TU Munich</A>. This group co-operates
+ − 88 with the <A HREF="http://www4.in.tum.de/proj/theoremprov/group.html">Theorem Proving Group</A>
+ − 89 chaired by <A HREF="http://www4.informatik.tu-muenchen.de/~nipkow/">Prof. Tobias Nipkow</A> and
+ − 90 is accommodated by the institute of
+ − 91 <A HREF="http://www4.informatik.tu-muenchen.de/~broy/">Prof. Manfred Broy</A>.
+ − 92 <P>
+ − 93
+ − 94 <B>Past Positions</B>
+ − 95 Between September 2008 and February 2009, I was an invited research fellow in
+ − 96 the <A HREF="http://www.cs.princeton.edu/">Department of Computer Science</A> in Princeton.
+ − 97 In 2004/05 I was an Alexander-von-Humboldt fellow in Munich and
+ − 98 from 2000 until 2004 I was awarded a Research Fellowship in Cambridge. Before that
+ − 99 I did my PhD in Cambridge.
+ − 100 <P>
+ − 101
+ − 102 <B>Research Interests</B> theorem provers, programming languages, compilers,
+ − 103 algorithms, proof theory, type systems, concurrency, lambda calculus, unification,
+ − 104 regular expressions, computability, complexity, functional and logic programming.
+ − 105 <P>
+ − 106
+ − 107 <B>Conferences</B>
+ − 108 <A HREF="http://www.iiia.csic.es/~levy/unif06/">UNIF'06</A> (member of PC),
+ − 109 <A HREF="http://www.cs.mcgill.ca/~bpientka/lfmtp07">LFMTP'07</A> (member of PC),
+ − 110 <A HREF="http://isabelle.in.tum.de/nominal/activities/lfmtp08/">LFMTP'08</A> (PC co-chair),
+ − 111 <A HREF="http://www.cis.upenn.edu/~sweirich/wmm/">WMM'08</A> (member of PC),
+ − 112 <A HREF="http://www.mat.ufmg.br/lsfa2008/">LSFA'08</A> (invited speaker),
+ − 113 <A HREF="http://www.dcs.kcl.ac.uk/staff/maribel/TAASN.html">TAASN'09</A> (member of PC),
+ − 114 <A HREF="http://lsfa09.cic.unb.br/">LSFA'09</A> (member of PC),
+ − 115 <A HREF="http://isabelle.in.tum.de/nominal/activities/tphols09/idw.html">IDW'09</A> (organiser),
+ − 116 <A HREF="http://www.seas.upenn.edu/~sweirich/wmm/wmm09.html">WMM'09</A> (PC chair),
+ − 117 <A HREF="http://tphols.in.tum.de/">TPHOLs'09</A> (PC co-chair),
+ − 118 <A HREF="http://dream.inf.ed.ac.uk/events/automatheo-2010/">Automatheo'10</A> (member of PC),
+ − 119 <A HREF="http://www.floc-conference.org/">ITP'10</A> (member of PC),
+ − 120 <A HREF="http://www.dcs.kcl.ac.uk/staff/maribel/UNIF.html">UNIF'10</A> (invited speaker),
+ − 121 <A HREF="http://www.cis.upenn.edu/~bcpierce/wmm/">WMM'10</A> (invited speaker),
+ − 122 <A HREF="http://isabelle.in.tum.de/nominal/activities/idw10/idw.html">IDW'10</A> (co-organiser),
+ − 123 <A HREF="http://formes.asia/cpp">CPP'11</A> (member of PC),
+ − 124 <A HREF="http://www.rdp2011.uns.ac.rs/rta/">RTA'11</A> (member of PC),
+ − 125 <A HREF="http://lfmtp11.cs.umn.edu">LFMTP'11</A> (member of PC)
+ − 126 <BR>
+ − 127
+ − 128 </TD>
+ − 129 </TR>
+ − 130
+ − 131 <TR>
+ − 132 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 133 <B>Nominal Isabelle</B>
+ − 134 I currently work on Nominal
+ − 135 <A HREF="http://isabelle.in.tum.de">Isabelle</A>. This is joint work with
+ − 136 <A HREF="http://wwwbroy.in.tum.de/~berghofe/">Dr Stefan Berghofer</A>,
+ − 137 <A HREF="http://www4.in.tum.de/~wenzelm/">Dr Markus Wenzel</A>,
+ − 138 <A HREF="http://www4.in.tum.de/~kaliszyk/">Dr Cezary Kaliszyk</A> and
+ − 139 the Isabelle-team in Munich.
+ − 140 Many of the theoretical ideas originate from the nominal logic project - a wonderful project headed
+ − 141 by <A HREF="http://www.cl.cam.ac.uk/~amp12/">Prof. Andrew Pitts</A>.
+ − 142 The aim of my work is to make formal reasoning involving binders as simple as
+ − 143 on paper and the hope is to lure
+ − 144 <A HREF="http://alliance.seas.upenn.edu/~plclub/cgi-bin/poplmark/index.php?title=The_POPLmark_Challenge#Vision">masses</A> to automated
+ − 145 theorem proving. My funding for this work was provided in 2004 and 2005 by a research
+ − 146 fellowship from the
+ − 147 <A HREF="http://en.wikipedia.org/wiki/Alexander_von_Humboldt">Alexander-von-Humboldt</A>
+ − 148 <A HREF="http://www.humboldt-foundation.de/web/home.html">foundation</A>. During this time I was a visitor in the group of
+ − 149 <A HREF="http://www.mathematik.uni-muenchen.de/~schwicht/">Prof. Helmut Schwichtenberg</A>.
+ − 150 Since 2006 this work is supported by an
+ − 151 <A HREF="http://en.wikipedia.org/wiki/Emmy_Noether">Emmy-Noether</A>
+ − 152 <A HREF="http://www.dfg.de/en/research_funding/programmes/individual/emmy_noether/in_brief/index.html">fellowship</A>.
+ − 153 There is a <A HREF="http://isabelle.in.tum.de/nominal/">webpage</A> and a
+ − 154 <A HREF="https://mailmanbroy.informatik.tu-muenchen.de/mailman/listinfo/nominal-isabelle">mailing list</A>
+ − 155 about Nominal Isabelle. It also includes a list of projects that use Nominal Isabelle.
+ − 156 Users of Nominal Isabelle had their papers appearing at LICS, POPL, FOSSACS, SOS, TPHOLs and CPP.
+ − 157 </TD>
+ − 158 </TR>
+ − 159
+ − 160 <TR>
+ − 161 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 162 <B>Myhill-Nerode and Regular Expressions</B>
+ − 163 Out of frustration of having to teach inductions in theorem provers using worn-out examples like
+ − 164 fib and even/odd, we implemented a large part of regular language theory in Isabelle/HOL.
+ − 165 This <A HREF="http://afp.sourceforge.net/devel-entries/Myhill-Nerode.shtml">implementation</A>
+ − 166 gives rise to much more interesting examples, as shown
+ − 167 <A HREF="http://www.cs.cmu.edu/~rwh/papers/regexp/jfp.ps">here</A> and
+ − 168 <A HREF="http://ropas.snu.ac.kr/~kwang/paper/06-jfp-yi.pdf">here</A>. It turns out that
+ − 169 formalisations of automata theory are a huge
+ − 170 <A HREF="https://lists.cam.ac.uk/pipermail/cl-isabelle-users/2005-September/msg00012.html">pain</A>
+ − 171 in theorem provers, especially in those that are HOL-based.
+ − 172 We therefore went against the
+ − 173 <A HREF="http://books.google.com/books?id=8lKyxS8_CNoC&pg=PA14&source=gbs_toc_r&cad=4#v=onepage&q&f=false">mainstream</A>
+ − 174 and used in our formalisation regular expressions exclusively,
+ − 175 because they are much more convenient for formal reasoning. The results we
+ − 176 formalised include: the Myhill-Nerode theorem, the closure of regular languages
+ − 177 under complementation, finiteness of derivatives of regular expressions and a surprising
+ − 178 result about Subseq, which according to
+ − 179 this
+ − 180 <A HREF="http://blog.computationalcomplexity.org/2006/01/theorem-that-should-be-better-known.html">blog</A>
+ − 181 should be better known. This is joint work with Prof. Xingyuan
+ − 182 Zhang and his student Chunhan Wu from the
+ − 183 <A HREF="http://www.ust.com.cn/">PLA University of Science and Technology</A> in Nanjing.
+ − 184 My funding for this work came from the
+ − 185 <A HREF="http://www.sinogermanscience.org.cn/">Chinese-German Research Centre</A>.
+ − 186 </TD>
+ − 187 </TR>
+ − 188
+ − 189 <TR>
+ − 190 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 191 <B>Nominal Unification and Alpha-Prolog</B>
3
+ − 192 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/Unification">Nominal unification</A> is one outcome of
2
+ − 193 my involvement in the nominal logic project in Cambridge. Another is the logic programming language
+ − 194 alpha-Prolog (joint work with <A HREF="http://homepages.inf.ed.ac.uk/jcheney/">Dr James Cheney</A>),
+ − 195 which uses nominal unification - click for details
+ − 196 <A HREF="http://homepages.inf.ed.ac.uk/jcheney/programs/aprolog/">here</A>.
+ − 197 The nominal unification algorithm has been
3
+ − 198 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/Unification">formally verified</A> in Isabelle. This
2
+ − 199 was possible since this unification algorithm is formulated in a simple first-order language
+ − 200 (unlike other algorithms for higher-order unification).
+ − 201 <A HREF="http://www.cs.indiana.edu/~dfried/">Prof. Daniel Friedman</A> and his group use nominal
+ − 202 unification in their alpha-Kanren system implemented in Scheme.
+ − 203 <A HREF="http://www.dcs.kcl.ac.uk/staff/maribel/">Prof. Maribel Fernandez</A> and her student
+ − 204 improved the nominal unification algorithm to be quadratic.
+ − 205 My funding for this work was provided through a research fellowship from
+ − 206 <A HREF="http://www.corpus.cam.ac.uk">Corpus Christi College</A>, Cambridge.
+ − 207 </TD>
+ − 208 </TR>
+ − 209
+ − 210 <TR>
+ − 211 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 212 <B>Classical Logic</B>
+ − 213 I was Ph.D. student in the University of Cambridge
+ − 214 <A HREF="http://www.cl.cam.ac.uk">Computer Laboratory</A>
+ − 215 and for three years
+ − 216 called Gonville and Caius College my home. I was very lucky to have
+ − 217 <A HREF="http://research.microsoft.com/~gmb/">Dr Gavin Bierman</A>
+ − 218 as supervisor. My research in Cambridge was also very much influenced by
+ − 219 <A HREF="http://www.dpmms.cam.ac.uk/~martin/">Prof. Martin Hyland</A>.
+ − 220 Some details on my thesis "Classical Logic and Computation" are
3
+ − 221 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/PhD/index.html">elsewhere</A>, including
+ − 222 a <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/Cut/cutapplet.html">Java Applet</A> that
2
+ − 223 'visualises' some of the results from the thesis. I completed the writing of
+ − 224 the thesis in <A HREF="http://iml.univ-mrs.fr/ldp/">Marseille</A> in the group of
+ − 225 <A HREF="http://iml.univ-mrs.fr/~girard/">Prof. Jean-Yves Girard</A>. My study in
+ − 226 Cambridge was funded by two <A HREF="http://www.daad.de/index.html">scholarships</a>
+ − 227 from the German government; my year in Marseille by a TMR-fellowship from the EU.
+ − 228 My PhD was also one starting point for the EPSRC Project on the Semantics of Classical
+ − 229 Proofs. The strong normalisation result in the PhD has recently been used by
+ − 230 <A HREF="http://www.loria.fr/~ckirchne/hot.html">Prof. Claude Kirchner</A> and his
+ − 231 students to prove consistency for their superdeduction system lemuridae.
+ − 232 </TD>
+ − 233 </TR>
+ − 234
+ − 235
+ − 236
+ − 237 <TR>
+ − 238 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 239 <B>Forum</B>
+ − 240 I implemented Forum, a programming language based on classical linear logic,
+ − 241 as my M.Phil. thesis. This was joint work with
+ − 242 <A HREF="http://www.dcs.st-and.ac.uk/~rd/">Dr Roy Dyckhoff</A>.
+ − 243 Details can be found
+ − 244 <A HREF="http://www.dcs.st-and.ac.uk/~rd/logic/nonmac/">here</A> and
+ − 245 <A HREF="http://www.lix.polytechnique.fr/Labo/Dale.Miller/forum/">here</A>. During my
+ − 246 M.Phil study I spent one month in Philadelphia invited by
+ − 247 <A HREF="http://www.lix.polytechnique.fr/~dale/">Prof. Dale Miller</A>.
+ − 248 </TD>
+ − 249 </TR>
+ − 250
+ − 251 <TR>
+ − 252 <TD BGCOLOR="#FFFFFF" WIDTH="75%">
+ − 253 <B>G4ip</B> An implementation of G4ip using the imperative language Pizza can be found
3
+ − 254 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/Prover/index.html">here</A>.
2
+ − 255 <A HREF="http://pizzacompiler.sourceforge.net">Pizza</A> is a conservative
+ − 256 extension of Java and a precursor of Scala. The implementation illustrates the technique of success
+ − 257 continuations.
+ − 258 </TD>
+ − 259 </TR>
+ − 260
+ − 261
+ − 262 </TABLE>
+ − 263 <P><!-- Created: Tue Mar 4 00:23:25 GMT 1997 -->
+ − 264 <!-- hhmts start -->
+ − 265 Last modified: Mon Sep 5 10:11:36 BST 2011
+ − 266 <!-- hhmts end -->
+ − 267 <a href="http://validator.w3.org/check/referer">[Validate this page.]</a>
+ − 268
+ − 269 <!-- script type="text/javascript">
+ − 270 var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
+ − 271 document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
+ − 272 </script>
+ − 273 <script type="text/javascript">
+ − 274 try {
+ − 275 var pageTracker = _gat._getTracker("UA-4143458-2");
+ − 276 pageTracker._trackPageview();
+ − 277 } catch(err) {}
+ − 278 </script -->
+ − 279 </BODY>
+ − 280 </HTML>