Friday, April 29, 2011

Quick reflections on ICALP 2011 (track B), part II: Conferences and long papers

During the review process for ICALP track B, a colleague wrote to me saying that he was planning to submit a paper longer than 70 pages to the conference, but eventually decided not to do so. While he was considering submitting the paper, this colleague was naturally wondering about the implications of submitting such a long paper to a conference with a 12-page limit on submissions. This academic told me that he thought that it would not be unreasonable to reject a very long paper submitted to ICALP  without even reading it. Such a decision could be backed up by a notification notice stating that "the paper is unverifiable given the available time and resources" or even "considering the paper is pointless since only 12 pages will be published."

I can understand very well why this colleague decided not to submit the paper to ICALP. Shrinking a 70+-page paper to 12 pages is a major effort, and one has to wonder whether a conference is the right outlet for such a lengthy piece of work. Indeed, one may argue that our conference publication structure does not lend itself to the publication of (very) long papers. However, I know of at least three exceptions (listed here in chronological order).
  1. The ICALP 1990 paper in which Daniel Krob presented his equational axiomatizations of equality of regular expressions was 14 pages long, but the journal paper Complete Systems of B-Rational Identities (solving two problems posed by John Horton Conway in his monograph Regular Algebra and Finite Machines) that appeared in TCS in 1991 was 137 pages long. 
  2. The ICALP paper in which Sénizergues introduced the decidability of DPDA equivalence is only 10 pages long, but the journal paper is 166 pages long.
  3. The short paper by Martin Grohe at was published in LICS 2010, but the full work takes a book that is still under development. See
Now, one might ask what the purpose of those conference papers is. In some sense, my colleague was right in saying that they are "unverifiable" (given the length and time constraints imposed by conferences). I doubt that the conference reviewers went through all the details of the full versions of those papers, when they were available. Even a journal reviewer would probably not do so.

I guess that the answer is simply that the conference versions announce the results and "mark the territory" by saying "I did it". However, IMHO, the results only stand after the interested community has not found any serious errors in the full versions of the papers for a long time.

A separate issue is that of writing a conference paper based on a long full paper, which does justice to the main results and techniques presented by the authors in the full version in all the gory details. IMHO, conference papers reporting  on very long and technical developments are "trailers"  for the full version of the story, which is told elsewhere in all its glory. As a movie trailer, the conference paper serves the purpose of enticing potential readers to check out the full version by motivating the work, putting it in context, stating the achieved results, discussing their importance and giving a high-level sketch of the techniques and of the tools involved in the proof. (I am thinking here, for example, of the above-mentioned paper Grohe published at last year´s LICS, where he did precisely what I wrote above and, to my mind, did it well.) Of course, this is easier said than done..

Wednesday, April 27, 2011

Quick reflections on ICALP 2011 (track B): French TCS is alive and well

This is the first in what I hope will be a series of posts devoted to some reflections on ICALP 2011 track B. The executive summary is that, for what it is worth, I believe that French TCS is alive and well (at least as far as volume B TCS is concerned).

France was the country with the largest number of track B authors (42), the largest number of submitted papers (21.79) and the largest number of accepted papers (7). Easychair statistics aside, France is home to some research groups in TCS that have amazing strength in depth and breadth. To wit, consider the following three exhibits, with apologies to those that I am unable to mention explicitly here.
  • Paris Diderot (aka Paris 7). This university is home to LIAFA and PPS, two large research laboratories hosting an enormous wealth of talent. (In passing, let me mention that PPS is a kind of little Italy, with six Italians holding permanent positions.)
  • LSV at ENS Cachan.  The Laboratoire Spécification et Vérification (LSV) is the Computer Science laboratory of ENS de Cachan, and was founded in 1997. I had the pleasure of spending a month there in May 1998 as a visiting professor, but the LSV of today hosts a much larger team of researchers than it did then. The list of members is impressive. When Hubert Comon received a CNRS silver medal in 2008, he said that "I think that this is the best environment in the world to carry out research in computer science, thanks to a unique way of working and to a great scientific homogeneity." (See here, page 34, for the French original.) Of course, one can always debate this kind of statements, but it is hard to question the strength and focus of that group of academics. 
  • LaBRI in Bordeaux. This is home to figures such as Bruno Courcelle, Anca Muscholl, Géraud Sénizergues, Igor Walukiewicz  and Pascal Weil, who are all members of the Formal Methods Group, which currently has 55 members.
It seems to me that these research centres are just the tip of a strong research iceberg in TCS. May they continue this way. 

    EATCS Award 2011 to Boris (Boaz) Trakhtenbrot

    The EATCS Award for 2011 will go to Boris (Boaz) Trakhtenbrot  for "his decisive influence on the developments of algorithms, and, more generally, of computer science as a whole in many ways." You can read a scientific "autobiography" written by Boaz for an LNCS volume devoted to his 85th birthday here (requires access to LNCS). I found the piece a fascinating read.

    Congratulation to Boaz.

    Here is what the EATCS web site says:

    The EATCS Award is awarded annually to honor a scientist with widely recognized contributions to the field of theoretical computer science throughout a distinguished scientific career. The Committee, consisting of Pavlos Spirakis (Chair), Friedhelm Meyer auf der Heide  and Eugenio Moggi in charge of evaluating the nominations to the 2011 EATCS Award has come to the decision to honor Boris (Boaz) Trakhtenbrot with the EATCS Award 2011 for his decisive influence on the developments of algorithms, and, more generally, of computer science as a whole in many ways.The decision has been unanimously approved by the EATCS Council. The Award will be assigned during a ceremony that will take place in Zürich (Switzerland) during ICALP 2011 (July 4-8, 2011).

    Friday, April 15, 2011

    Best paper awards at ICALP 2011

    The best paper awards for the three tracks at ICALP 2011 will go to the following papers:

    Track A

    Track B
    • Olivier Carton, Thomas Colcombet and Gabriele Puppis. Regular Languages of Words Over Countable Linear Orderings.
    •  Martin Delacourt. Rice's theorem for mu-limit sets of cellular automata. (Best student paper)

    Track C
    • Martin Hoefer.Local Matching Dynamics in Social Networks.
    • Shiri Chechik. Fault-Tolerant Compact Routing Schemes for General Graphs. (Best student paper)
    Congratulations to all the awardees!

      Wednesday, April 13, 2011

      Accepted papers for ICALP 2011 tracks A and C

      The lists of accepted papers for ICALP 2011 tracks A and C are now available from the web site for the conference (both with and without abstracts). See here for track A and here for track C. I am no expert, but the lists of accepted papers look very impressive to me. It is also clear that blogging has a positive influence on acceptance of one's papers at ICALP track A :-) Congrats to Andrew, Bill, Lance and Scott, with apologies to other volume A bloggers I might have missed.

      Tuesday, April 12, 2011

      Source of a quote by Lazlo Babai

      I once read the following quote attributed to Lazlo Babai: "What we need are not more theorems, but more proofs." I think that I originally read it on his Wikipedia entry, but the quote is not there anymore.

      Can anyone tell me from where the quote originates, assuming my memory is not playing tricks with me? Thanks in advance!

      Accepted papers for ICALP 2011 track B

      The notifications and the reviews for ICALP 2011 were posted earlier today. I was the PC chair for track B and I freely admit that, during the electronic PC meeting,  I often felt that the job was too big for me. I owe all of my PC a great debt. I could not have mastered this PC chair job without the support of the members of the PC and without relying on their scientific judgement and professionalism. Indeed, I feel that I have learned a lot from my PC during the meeting.

      The overall quality of the submissions to ICALP 2011 track B was unbelievably high. (My co-chairs tell me a similar story for the other two tracks, and this bodes well for the future of ICALP.) I feel that I have never been involved in the PC for a conference where the threshold for acceptance was so high. I wish that we could have selected at least ten more papers, but the number of slots was limited and we had to make some very hard choices. The authors of the many good papers that we could not select have my sympathy. I have no doubt that they will publish their submissions in a top-notch conference and/or journal soon.

      There are several interesting topics for discussion that emerge from the field of submissions at this year's ICALP track B. I plan to devote a short series of posts to some of those that I have penned down during the PC meeting. However, this will have to wait until I have caught up with some of the many chores that have piled up on my desk over the last two months. For the moment, the list of accepted papers for track B is here. (See here for the list with abstracts.)

      I look forward to a very exciting meeting in Zürich in July.

      Saturday, April 09, 2011

      Student Scholarships at ICALP 2011

      If you are a student and you are planning to attend ICALP 2011, read below. 

      The EATCS (partly sponsored by MPI-INF) has provided ten 500-Euro student scholarships.  The ten scholarships will be used to support participation of students in ICALP 2011 by covering early registration and possibly some of the local expenses.

      To apply for one of these scholarships, please send an email to . The application should be sent by April 19th, 2011, and should contain a motivation for the sponsorship request, one letter of recommendation, the curriculum vitae of the applicant, together with an indication of whether the applicant is an author or co-author of one of the papers selected for the conference.

      The applications will be reviewed by the ICALP 2011 conference chairs and the PC chairs. Preference will be given to PhD students from countries where access to funds is limited who will present papers at the conference. Each applicant will receive a notification of acceptance/rejection of her/his application by email by April 30th, 2011.