Archive for the ‘Publications’ Category.

Computing: the Art, the Magic, the Science


My colleagues and I have just finished recording our new MOOC (online course), an official ETH offering on the EdX platform. The preview is available [1] and the course will run starting in September.

As readers of this blog know, I  have enthusiastically, under the impulsion of Marco Piccioni at ETH, embraced MOOC technology to support and spread our courses. The particular target has been the introduction to programming that I have taught for over a decade at ETH based on the Touch of Class textbook [2]. In February this blog announced [3] the release of our first MOOC, embodying the essentials of our ETH course and making it available not only to ETH students but to the whole world. The course does not just include video lectures: it also supports active student participation through online exercises and programs that can be compiled and tested on the cloud, with no software installation. These advanced features result from our research on support for distributed software development (by Christian Estler and Martin Nordio, with Carlo Furia and others).

This first course was a skunkworks project, which we did entirely on our own without any endorsement from ETH or any of the main MOOC players. We and our students have very much benefited from the consequent flexibility, and the use of homegrown technology relying on the MOODLE framework. We will keep this course for our own students and for any outside participant who prefers a small-scale, “boutique” version. But the EdX brand and EdX’s marketing power will enable us to reach a much broader audience. We want to provide the best introductory computing course on the market and the world needs to know about it. In addition, the full support of media services at ETH  helped us reach a higher standard on the technical side. (For our first course, the home-brewed one, we did not have a studio, so that every time an ambulance drove by — our offices are close to the main Zurich hospital — we had to restart the current take.)

The course’s content is not exactly the same: we have broadened the scope from just programming to computing, although it retains a strong programming component. We introduced additional elements such as an interview with Professor Peter Widmayer of ETH on the basics of computer science theory. For both new material and the topics retained from the first version we have adapted to the accepted MOOC practice of short segments, although we did not always exactly meet the eight-minute upper limit that was suggested to us.

We hope that you, and many newcomers, will like the course and benefit from it.


[3] EdX course: Computing: Art, Magic, Science, preview available here.

[2] Bertrand Meyer: Touch of Class: Learning how to Program Well, with Objects and Contracts, Springer Verlag, revised printing, 2013, book page here.

[3] Learning to Program, Online: article from this blog, 3 February 2014, available here.



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When pictures lie


One of the most improvable characteristics of scientific papers is the graphical presentation of numerical data. It is sad to see that thirty years after Tufte published the first edition of his masterpiece [1] many authors are still including grossly inaccurate graphics. Sadder still when the authors are professional graphists, who should know better. Take this chart [2] from the last newsletter of Migros, Switzerland’s largest supermarket chain. To convince Swiss people that they should not worry about their food bills, it displays the ratio of food expenses to revenue in various countries. There would be many good ways to represent this information graphically, but someone thought it clever to draw variable-size coins of the respective currencies. According to the text, “the bigger the circle, the larger the income’s share devoted to food“.

Just a minor problem: the visual effect is utterly misleading. Taking three examples from the numbers given, the ratio is roughly 10% for Switzerland, 30% for Russia, 40% for Morocco. And, sure enough,  compared to the Swiss coin in the figure, the Russian coin is about three times bigger and the Moroccan coin four times… in diameter! What the eye sees, of course, is the area. Since the area varies as the square of the diameter, one gets the impression that Russians spend nine times, not three, and Moroccans sixteen times, not four, as much as the Swiss.

To convey the correct suggestion, the diameter of the Russian coin should have been about 73% larger than the Swiss coin’s diameter (the square root of three is about 1.73) , and the diameter of the Moroccan coin twice larger, that is to say half of what it is.

The impression is particularly misleading for countries where the ratio, unlike in Russia or Morocco, is close to Switzerland’s. Most interestingly, although no doubt by accident, for neighboring countries, where Swiss people are prone to go shopping in search of a bargain, a practice that possibly does not enthuse Migros. The extra percentage devoted to food (using this time  no longer rough approximations but precise values from the figures given in the Migros page) is 4% for Austria (10.9 ratio vs Switzerland’s 10.2), 8% for Germany (11.1), 30% for France (13.3) and  43% for Italy (14.6). But if you look at the picture the circles suggest much bigger differences; for example the Italian circle is obviously computed from the ratio of the squares, 14.62 / 10.62, showing an increase of 104%. In other words, Italians proportionally devote to food a little over two-fifths more  than the Swiss, but the graph suggests they spend twice as much.

On the premise that one should not ascribe to malevolence what can be explained by ignorance, I hope the Migros graphists will get a copy of Tufte’s book for their future endeavors.

Read Tufte too if you want the pictures in your papers to be not just attractive but accurate.


[1] Edward R. Tufte: The Visual Display of Quantitative Information, Graphics Press, second edition, 2001. See his site here.

[2] “How much do we spend to feed ourselves?” on the Migros site, available here for the French version (replace “fr” in the URL by “de” for German and “it” for Italian, I did not see an English version). Click on the figure for a readable version.

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The Eiffel Documentation Drive

EiffelStudio releases are semi-annual, end of May and end of November. Release 14-05 just came out. The next release (14-11) is entirely devoted to documentation. We are hoping for extensive community involvement in this first-time Eiffel Documentation Drive.

Many people regularly comment that there is not enough Eiffel and EiffelStudio documentation, and some of what exists is not good enough. We have decided to tackle the problem seriously, hence the dedication of an entire release cycle to documentation. The term is taken here in a broad sense: “documentation” means what is at, but also everything else that can help understand Eiffel, for example updating Wikipedia entries on topics for which Eiffel has something to offer.

Anyone with an understanding of an Eiffel-related topic can help. We particularly need help from two (non-disjoint) categories of contributors

  • Those with a good understanding of one or more Eiffel-related topics.
  • Those with good writing skills.

The process will involve reviewing, so if you are an Eiffelist with moderate taste for writing, or a good writer with incomplete knowledge of Eiffel, we need your help anyway; someone else will compensate for the missing side. In particular, a common criticism is that some of the documentation was written by developers who do not have English as their mother tongue; if you can help improve it everyone will benefit. Of course if you are good at both technology and writing it’s even better.

We are mentioning English because it is the first target, but documentation in other languages, either original or a translation of existing English pages, is needed too.

Here is how the Eiffel Documentation Drive works:

  • Here you will find a form to report missing or unsatisfactory documentation. Please fill it on every applicable occasion.
  • The entries will be read by a member of the Eiffel Software team, who in applicable cases will add a row to the Eiffel Documentation Drive spreadsheet here. You can not only read that spreadsheet but also edit it yourself, so as to keep it as accurate and up-to-date as possible.
  • An email will be sent to the user list, with “Eiffel Documentation Drive” in the header (so that people not interested in the topic can filter them out), requesting help.
  • Those willing to help can enter their names in the corresponding row, indicating a planned date of completion.

Each row includes among its fields the following: topic, link to existing documentation, volunteer writer(s), planned completion, volunteer reviewer(s).

The full Eiffel Software team will participate – as noted above, improving the documentation is the strategic goal for the release – but we hope for considerable community participation. Please help make EiffelStudio documentation shine as much as the environment itself.

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Lamport, Turing


Theories abound (I have my own) about why it did not happen long ago, but at last Lamport did receive the Turing Award. For me what most characterizes him is a stream [1] of elegant, original, insightful articles providing solutions to one important and thorny problem after another. Some of these articles are well known but many gems are not; see for example his take on Buridan’s Ass [2], not even a computer science paper, offering a convincing treatment of a centuries-old riddle.


[1] Leslie Lamport: annotated publication list, here.

[2] Leslie Lamport: Buridan’s Principle, “to appear in Foundations of Physics“, dated 24 February 2012, available here.

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Agile book announced

My book “Agile! The Good, the Hype and the Ugly” will be published in a few weeks by Springer. The announced date is April 30 and there is a preview Amazon page: here.

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Eiffel as an expression language

A functional-programming style, or more generally a style involving more expressions and fewer instructions, is possible in Eiffel. In particular, Eiffel’s agent mechanism embeds a full functional-programming mechanism in the object-oriented framework of the language.

To make the notations simpler, we are discussing and tentatively implementing a number of proposed extensions. They involve no fundamental new language mechanisms, but provide new, more concise notations for existing mechanisms. Examples are:

  • Conditional expressions.
  • Implicit tuple, a rule allowing the omission of brackets for an actual argument when it is a tuple and the last argument, e.g. f (x, y, z) as an abbreviation for f ([x, y, z]) (an example involving just one argument). Tuples already provided the equivalent of a variable-argument (“varargs”) facility, but it is made simpler to use with this convention.
  • Parenthesis alias, making it possible to write just f (x, y) when f is an agent (closure, lambda expression, delegate etc. in other terminologies), i.e. treating f as if it were a function; the notation is simply an abbreviation for f.item ([x, y]) (an example that also takes advantage of implicit tuples). It has many other applications since a “parenthesis alias” can be defined for a feature of any class.
  • Avoiding explicit assignments to Result.
  • Type inference (to avoid explicitly specifying the type when it can be deduced from the context). This is a facility for the programmer, useful in particular for local variables, but does not affect the type system: Eiffel remains strongly typed, it is just that you can be lazy about writing the type when there is no ambiguity.
  • In the same vein, omitting the entire list of generic parameters when it can be inferred.

The description of the mechanism (see the link in [1]) is in the form of a set of slides explaining the concepts and presenting example. This is a working document and feedback is welcome.


[1] Eiffel as an expression language, Eiffel Software working document, 2012-2014, see here.

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Informatics education in Europe: Just the facts


In 2005 a number of us started Informatics Europe [1], the association of university departments and industrial research labs in computer science in Europe. The association has now grown to 80 members across the entire continent; it organizes the annual European Computer Science Summit and has published a number of influential reports. The last one just came out: Informatics Education in Europe: Institutions, Degrees, Students, Positions, Salaries — Key Data 2008-2012 [2]. The principal author is Cristina Pereira, who collected and organized the relevant data over more than a year; I helped with the preparation of the final text.

At the beginning of Informatics Europe we considered with particular attention  the model of the Computing Research Association [3], which played a crucial role in giving computer science (informatics) its due place in the US academic landscape. Several past and current officers of the CRA,  such as Willy Zwaenepoel, Ed Lazowska, Bob Constable, Andy Bernat, Jeannette Wing, Moshe Vardi and J Strother Moore gave keynotes at our early conferences and we of course asked them for the secrets of their organization’s success. One answer that struck us was the central role played by data collection. Just gathering the  facts, such as degrees and salaries, established for the first time a solid basis for serious discussions. We took this advice to heart and the report is the first result.

Gathering the information is particularly difficult for Europe given the national variations and the absence of centralized statistical data. Even the list of names under which institutions teach informatics in Europe fills a large table in the report. Cristina’s decision was, from the start, to favor quality over quantity: to focus on impeccable data for countries for which we could get it, rather than trying to cover the whole continent with data of variable credibility.

The result is the first systematic repository of basic information on informatics education in Europe: institutions, degrees offered and numbers awarded, student numbers, position titles and definitions, and (a section which will not please everyone) salaries for PhD students, postdocs and professors of various ranks.

The report is a first step; it only makes sense if we can regularly continue to update it and particularly extend it to other countries. But even in its current form (and with the obvious observation that my opinion is not neutral)  I see it as a major step forward for the discipline in Europe. We need an impeccable factual basis to convince the public at large and political decision-makers to give informatics the place it deserves in today’s educational systems.


[1] Informatics Europe site, see here.

[2] Cristina Pereira and Bertrand Meyer: Informatics Education in Europe: Institutions, Degrees, Students, Positions, Salaries — Key Data 2008-2012, Informatics Europe report, 30 September 2013, available here.

[3] Computing Research Association (US), see here.


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The secret of success

In the process of finishing a book right now, it occurred to me that writing is really a simple matter. There are only three issues to address:

  1. How to start.
  2. How to finish.
  3. How to take care of the stuff in-between.

In the early stages  (1) you face the anguish of the “empty paper, defended by its whiteness” (Mallarmé) and do not know where to begin. If you overcome it, you have all the grunt work to do (3), step after step. At the end (2), while deep down you feel you have done enough and should be permitted to  click “Publish”, you still have to fill the holes, which may be small in number but have remained holes for a reason: you have again and again delayed filling them because in reality you do not know what to write there.

All things considered, then, it is not such a big deal.

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Reading notes: misclassified bugs


(Please note the general disclaimer [1].)

How Misclassification Impacts Bug Prediction [2], an article to be presented on Thursday at ICSE, is the archetype of today’s successful empirical software engineering research, deriving significant results from the mining of publicly available software project repositories — in this case Tomcat5 and three others from Apache, as well as Rhino from Mozilla. The results are in some sense meta-results, because many studies have already mined the bug records of such repositories to draw general lessons about bugs in software development; what Herzig, Just and Zeller now tell us is that the mined data is highly questionable: many problems classified as bugs are not bugs.

The most striking results (announced in a style a bit stentorian to my taste, but indeed striking) are that: every third bug report does not describe a bug, but a request for a new feature, an improvement, better documentation or tests, code cleanup or refactoring; and that out of five program files marked as defective, two do not in fact contain any bug.

These are both false positive results. The repositories signal very few misclassifications the other way: only a small subset of enhancement and improvement requests (around 5%) should have been classified as bugs, and even fewer faulty files are missed (8%, but in fact less than 1% if one excludes an outlier, tomcat5 with 38%, a discrepancy that the paper does not discuss).

The authors have a field day, in the light of this analysis, of questioning the validity of the many studies in recent years — including some, courageously cited, by Zeller himself and coauthors — that start from bug repositories to derive general lessons about bugs and their properties.

The methodology is interesting if a bit scary. The authors (actually, just the two non-tenured authors, probably just a coincidence) analyzed 7401 issue reports manually; more precisely, one of them analyzed all of them and the second one took a second look at the reports that came out from the first step as misclassified, without knowing what the proposed reclassification was, then the results were merged. At 4 minutes per report this truly stakhanovite effort took 90 working days. I sympathize, but I wonder what the rules are in Saarland for experiments involving living beings, particularly graduate students.

Precise criteria were used for the reclassification; for example a report describes a bug, in the authors’ view, if it mentions a null pointer exception (I will skip the opportunity of a pitch for Eiffel’s void safety mechanism), says that the code has to be corrected to fix the semantics, or if there is a “memory issue” or infinite loop. These criteria are reasonable if a bit puzzling (why null pointer exceptions and not other crashes such as arithmetic overflows?); but more worryingly there is no justification for them. I wonder  how much of the huge discrepancy found by the authors — a third or reported bugs are not bugs, and 40% of supposedly defective program files are not defective — can be simply explained by different classification criteria applied by the software projects under examination. The authors give no indication that they interacted with the people in charge of these projects. To me this is the major question hovering over this paper and its spectacular results. If you are in the room and get the chance, don’t hesitate to ask this question on my behalf or yours!

Another obvious question is how much the results depend on the five projects selected. If there ever was room for replicating a study (a practice whose rarity in software engineering we lament, but whose growth prospects are limited by the near-impossibility of convincing selective software engineering venues to publish confirmatory empirical studies), this would be it. In particular it would be good to see some of the results for commercial products.

The article offers an explanation for the phenomena it uncovered: in its view, the reason why so many bug reports end up misclassified is the difference of perspective between users of the software, who complain about the problems they encounter,  and the software professionals  who prepare the actual bug reports. The explanation is plausible but I was surprised not to see any concrete evidence that supports it. It is also surprising that the referees did not ask the authors to provide more solid arguments to buttress that explanation. Yet another opportunity to raise your hand and ask a question.

This (impressive) paper will call everyone’s attention to the critical problem of data quality in empirical studies. It is very professionally prepared, and could, in addition to its specific contributions, serve as a guide on how to get an empirical software engineering paper accepted at ICSE: take a critical look at an important research area; study it from a viewpoint that has not been considered much so far; perform an extensive study, with reasonable methodological assumptions; derive a couple of striking results, making sure they are both visibly stated and backed by the evidence; and include exactly one boxplot.

Notes and references

[1] This article review is part of the “Reading Notes” series. General disclaimer here.

[2] Kim Herzig, Sascha Just and Andreas Zeller: It’s not a Bug, it’s a Feature: How Misclassification Impacts Bug Prediction, in ICSE 2013, available here. According to the ICSE program the paper will be presented on May 23 in the Bug Prediction session, 16 to 17:30.

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Presentations at ICSE and VSTTE


The following presentations from our ETH group in the ICSE week (International Conference on Software Engineering, San Francisco) address important issues of software specification and verification, describing new techniques that we have recently developed as part of our work building EVE, the Eiffel Verification Environment. One is at ICSE proper and the other at VSTTE (Verified Software: Tools, Theories, Experiments). If you are around please attend them.

Julian Tschannen will present Program Checking With Less Hassle, written with Carlo A. Furia, Martin Nordio and me, at VSTTE on May 17 in the 15:30-16:30 session (see here in the VSTTE program. The draft is available here. I will write a blog article about this work in the coming days.

Nadia Polikarpova will present What Good Are Strong Specifications?, written with , Carlo A. Furia, Yu Pei, Yi Wei and me at ICSE on May 22 in the 13:30-15:30 session (see here in the ICSE program). The draft is available here. I wrote about this paper in an earlier post: see here. It describes the systematic application of theory-based modeling to the full specification and verification of advanced software.

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The waves of publication

(This article first appeared in the Communications of the ACM blog.)

The very concept of publication has changed, half of its traditional meaning having disappeared in hardly more than a decade. Or to put it differently (if you will accept the metaphor, explained below), how it has lost its duality: no longer particle, just wave.

Process and product

Some words ending with ation (atio in Latin) describe a change of state: restoration, dilatation. Others describe the state itself, or one of its artifacts: domination, fascination. And yet others play both roles: decoration can denote either the process of embellishing (she works in interior decoration), or an element of the resulting embellishment (Christmas tree decoration).

Since at least Gutenberg, publication has belonged to that last category: both process and artifact. A publication is an artifact, such as an article or a book accessible to a community of readers. We are referring to that view when we say “she has a long publication list or “Communications of the ACM is a prestigious publication.” But the word also denotes a process, built from the verb “publish” the same way “restoration” is built from “restore” and “insemination” from “inseminate”: the publication of her latest book took six months.

The thesis of this article is that the second view of publication will soon be gone, and its purpose is to discuss the consequences for scientists.

Let me restrict the scope: I am only discussing scientific publication, and more specifically the scientific article. The situation for books is less clear; for all the attraction of the Kindle and other tablets, the traditional paper book still has many advantages and it would be risky to talk about its demise. For the standard scholarly article, however, electronic media and the web are quickly destroying the traditional setup.

That was then . . .

Let us step back a bit to what publication, the process, was a couple of decades ago. When you wrote something, you could send it by post to your friends (Edsger Dijkstra famously turned this idea into his modus operandi, regularly xeroxing his “EWD” memos [1] to a few dozen people) , but if you wanted to make it known to the world you had to go through the intermediation of a PUBLISHER — the mere word was enough to overwhelm you with awe. That publisher, either a non-profit organization or a commercial house, was in charge not only of selecting papers for a conference or journal but of bringing the accepted ones to light. Once you got the paper accepted began a long and tedious process of preparing the text to the publisher’s specifications and correcting successive versions of “galley proofs.” That step could be painful for papers having to do with programming, since in the early days typesetters had no idea how to lay out code. A few months or a couple of years later, you received a package in the mail and proudly opened the journal or proceedings at the page where YOUR article appeared. You would also, usually for a fee, receive fifty or so separately printed (tirés à part) reprints of just your article, typeset the same way but more modestly bound. Ah, the discrete charm of 20-th century publication!

. . . and this is now

Cut to today. Publishers stopped long ago to do the typesetting for you. They impose the format, obligingly give you LaTex, Word or FrameMaker templates, and you take care of everything. We have moved to WYSIWYG publishing: the version you write is the version you submit through a site such as EasyChair or CyberChair and the version that, after correction, will be published. The middlemen have been cut out.

We moved to this system because technology made it possible, and also because of the irresistible lure, for publishers, of saving money (even if, in the long term, they may have removed some of the very reasons for their existence). The consequences of this change go, however, far beyond money.

Integrating change

To understand how fundamentally the stage has changed, let us go back for a moment to the old system. It has many advantages, but also limitations. Some are obvious, such as the amount of work required, involving several people, and the delay from paper completion to paper publication. But in my view the most significant drawback has to do with managing change. If after publication you find a mistake, you must convince the journal to include an erratum: a new mini-article, subject to the same process. That requirement is reasonable enough but the scheme does not support a significant mode of scientific writing: working repeatedly on a single article and progressively refining it. This is not the “LPU” (Least Publishable Unit) style of publishing, but a process of studying an important idea or research project and aiming towards the ideal paper about it by successive approximation. If six months after the original publication of an article you have learned more about the topic and how to present it, the publication strategy is not obvious: resubmit it and risk being accused of self-plagiarism; avoid repetition of basic elements, making the article harder to read independently; artificially increase differences. This conundrum is one of the legitimate sources of the LPU phenomenon: faced with the choice between freezing material and repeating it, people end up publishing it bit by bit.

Now back again to today. If you are a researcher, you want the world to know about your ideas as soon as they are in a clean form. Today you can do this easily: no need to photocopy page after page and lick postage stamps on envelopes the way Dijkstra did; just generate a PDF and put it on your Web page or (to help establish a record if a question of precedence later comes up) on ArXiv. Just to make sure no one misses the information, tweet about it and announce it on your Facebook and LinkedIn pages. Some authors do this once the paper has been accepted, but many start earlier, at the time of submission or even before. I should say here that not all disciplines allow such author behavior; in biology and medicine in particular publishers appear to limit authors’ rights to distribute their own texts. Computer scientists would not tolerate such restrictions, and publishers, whether nonprofit or commercial, largely leave us alone when we make our work available on the Web.

But we are talking about far more than copyright and permissions (in this article I am in any case staying out of these emotionally and politically charged issues, open access and the like, and concentrating on the effect of technology changes on the process of publishing and the publication culture). The very notion of publication has changed. The process part is gone; only the result remains, and that result can be an evolving product, not a frozen artifact.

Particle, or wave?

Another way to describe the difference is that a traditional publication, for example an article published in a journal, is like a particle: an identifiable material object. With the ease of modification, a publication becomes more like a wave, which allows an initial presentation to propagate to successively wider groups of readers:Waves of publication

Maybe you start with a blog entry, then you register the first version of the work as a technical report in your institution or on ArXiv, then you submit it to a workshop, then to a conference, then a version of record in a journal.

In the traditional world of publication each of these would have to be made sufficiently different to avoid the accusation of plagiarism. (There is some tolerance, for example a technical report is usually not considered prior publication, and it is common to submit an extended version of a conference paper to a journal — but the journal will require that you include enough new material, typically “at least 30%.”)

For people who like to polish their work repeatedly, that traditional model is increasingly hard to accept. If you find an error, or a better way to express something, or a complementary result, you just itch to make the change here and now. And you can. Not on a publisher’s site, but on your own, or on ArXiv. After all, one of the epochal contributions of computer technology, not heralded loudly enough, is, as I argued in another blog article [2], the ease with which we can change, extend and refine our creations, developing like a Beethoven and releasing like a Mozart.

The “publication as product” becomes an evolving product, available at every step as a snapshot of the current state. This does not mean that you can cover up your mistakes with impunity: archival sites use “diff” techniques to maintain a dated record of successive versions, so that in case of doubt, or of a dispute over precedence,  one can assess beyond doubt who released what statement when. But you can make sure that at any time the current version is the one you like best. Often, it is better than the official version on the conference or journal site, which remains frozen forever in the form it had on the day of its release.

What then remains of “publication as process”? Not much; in the end, a mere drag-and-drop from the work folder to the publication folder.

Well, there is an aspect I have not mentioned yet.

The sanction

Apart from its material side, now gone or soon to be gone, the traditional publication process has another role: what a recent article in this blog [3] called sanction. You want to publish your latest scientific article in Communications of the ACM not just because it will end up being printed and mailed, but because acceptance is a mark of recognition by experts. There is a whole gradation of prestige, well known to researchers in every particular field: conferences are better than workshops, some journals are as good as conferences or higher, some conferences are far more prestigious than others, and so on.

That sanction, that need for an independent stamp of approval, will remain (and, for academics, young academics in particular, is of ever growing importance). But now it can be completely separated from the publication process and largely separated (in computer science, where conferences are so important today) from the conference process.

Here then is what I think scientific publication will become. The researcher (the author) will largely be in control of his or her own text as it goes through the successive waves described above. A certified record will be available to verify that at time t the document d had the content c. Then at specific stages the author will submit the paper. Submit in the sense of appraisal and, if the appraisal is succesful, certification. The submission may be to a conference: you submit your paper for presentation at this year’s ICSE, POPL or SIGGRAPH. (At the recent Dagstuhl publication culture workshop, Nicolas Holzschuch mentioned that some graphics conferences accept for presentation work that has already been published; isn’t this scheme more reasonable than the currently dominant practice of conference-as-publication?) You may also submit your work, once it reaches full maturity, to a journal. Acceptance does not have to mean that any trees get cut, that any ink gets spread, or even that any bits get moved: it simply enables the journal’s site to point to the article, and your site to add this mark of recognition.

There may also be other forms of recognition, social-network or Trip Advisor style: the community gets to pitch in, comment and assess. Don’t laugh too soon. Sure, scientific publication has higher standards than Wikipedia, and will not let the wisdom of the crowds replace the judgment of experts. But sometimes you want to publish for communication, not sanction; especially if you have the privilege of no longer being trapped in the publish-or-perish race you may simply want to make your research known, and you have little patience for navigating the meanders of conventional publication, genuflecting to the publications of PC members, and following the idiosyncratic conventional structure of the chosen conference community. Then you just publish and let the world decide.

In most cases, of course, we do need the sanction, but there is no absolute reason it should be tied to the traditional structures of journal publication and conference participation. There will be resistance, if only because of the economic interests involved; some of what we know today will remain, albeit with a different focus: conferences, as a place where the best work of the moment is presented (independently of its publication); printed books, as noted;  and printed journals that bring real added value in the form of high-quality printing, layout and copy editing (and might still insist that you put on their site a copy of your paper rather than, or in addition to, a reference to your working version).

The trend, however, is irresistible. Publication is no longer a process, it is a product, increasingly under the control of the authors. As a product it is no longer a defined particle but a wave, progressively improving as it reaches successive classes of readership, undergoes successive steps of refinement and receives, informally from the community and officially from more or less prestigious sources, successive stamps of approval.


[1] Dijkstra archive at the University of Texas at Austin, here.

[2] Bertrand Meyer: Computer Technology: Making Mozzies out of Betties, article on this blog, 2 August 2009, available here.

[3] Bertrand Meyer: Conferences: Publication, Communication, Sanction, article on this blog, 6 February 2013, available here.

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Conferences: Publication, Communication, Sanction

Recycled(This article was first published in the Communications of the ACM blog.)

A healthy discussion is taking place in the computer science community on our publication culture. It was spurred by Lance Fortnow’s 2009 article [1]; now Moshe Vardi has taken the lead to prepare a report on the topic, following a workshop in Dagstuhl in November [2]. The present article and one that follows (“The Waves of Publication”)  are intended as contributions to the debate.

One of the central issues is what to do with conferences. Fortnow had strong words for the computer science practice of using conferences as the selective publication venues, instead of relying on journals as traditional scientific disciplines do. The criticism is correct, but if we look at the problem from a practical perspective it is unlikely that top conferences will lose their role as certifiers of quality. This is not a scientific matter but one of power. People in charge of POPL or OOPSLA have decisive sway over the careers (one is tempted to say the lives) of academics, particularly young academics, and it is a rare situation in human affairs that people who have critical power voluntarily renounce it. Maybe the POPL committee will see the light: maybe starting in 2014 it will accept all reasonable papers somehow related to “principles of programming languages”, turn the event itself into a pleasant multi-track community affair where everyone in the field can network, and hand over the selection and stamp-of-approval job to a journal such as TOPLAS. Dream on; it is not going to happen.

We should not, however, remain stuck with the status quo and all its drawbacks. That situation is unsustainable. As a single illustration, consider the requirement, imposed by all conferences, that having a paper pass the refereeing process is not enough: you must also register. A couple of months before the conference, authors of accepted papers (at least, they thought their paper was accepted) receive a threatening email telling them that unless they register and pay their paper will not be published after all. Now assume an author, in a field where a conference is the top token of recognition, has his visa application rejected by the country of the conference — a not so uncommon situation — and does not register. (Maybe he does not mind paying the fee, but he does not want to lie by pretending he is going to attend whereas he knows he will not.) He has lost his opportunity for publication and perhaps severely harmed this career. What have such requirements to do with science?

To understand what can be done, we need to analyze the role of conferences. In an earlier article  [3] I described four “modes and uses” of publication: Publication, Exam, Business and Ritual. From the organizers’ viewpoint, ignoring the Business and Ritual aspects although they do play a significant role, a conference has three roles: Publication, Communication and Sanction. The publication part corresponds to the proceedings of the conference, which makes articles available to the community at large, not just the conference attendees. The communication part only addresses the attendees: it includes the presentation of papers as well as all other interactions made possible by being present at a conference. The sanction part (corresponding to the “exam” part of the more general classification) is the role of a renowned conference as a stamp of approval for the best work of the moment.

What we should do is separate these roles. A conference can play all three roles, but it can also select two of them, or even just one. A well-established, prestigious conference will want to retain its sanctioning role: accepted papers get the stamp of approval. It will also remain an event, where people meet. And it may distribute proceedings. But the three roles can also be untied:

  • Publication is the least critical, and can easily be removed from the other two, since everything will be available on the Web. In fact the very notion of proceedings is quickly becoming fuzzy: more and more conferences save money by not distributing printed proceedings to attendees, sometimes not printing any proceedings at all; and some even spare themselves the production of a proceedings-on-a-stick, putting the material on the Web instead. A conference may still decide to have its own proceedings, or it might outsource that part to a journal. Each conference will make these decisions based on its own culture, tradition, ambition and constraints. For authors, the decision does not particularly matter: what counts are the sanction, which is provided by the refereeing process, and the availability of their material to the world, which will be provided in any scenario (at least in computer science where we have, thankfully, the permission to put our papers on our own web sites, an acquired right that our colleagues from other disciplines do not all enjoy).
  • Separating sanction from communication is a natural step. Acceptance and participation are two different things.

Conference organizers should not be concerned about lost revenue: most authors will still want to participate in the conference, and will get the funding since institutions are used to pay for travel to present accepted papers; some new participants might come, attracted by more interaction-oriented conference styles; and organizers can replace the requirement to register by a choice between registering and paying a publication fee.

Separating the three roles does not mean that any established conference renounces its sanctioning status, acquired through the hard work of building the conference’s reputation, often over decades. But everyone gets more flexibility. Several combinations are possible, such as:

  • Sanction without communication or publication: papers are submitted for certification through peer-review, they are available on the Web anyway, and there is no need for a conference.
  • Publication without sanction or communication: an author puts a paper on his web page or on a self-publication site such as ArXiv.
  • Sanction and communication without publication: a traditional selective conference, which does not bother to produce proceedings.
  • Communication without sanction: a working conference whose sole aim is to advance the field through presentations and discussions, and accepts any reasonable submission. It may be by invitation (a kind of advance sanction). It may have proceedings (publication) or not.

Once we understand that the three roles are not inextricably tied, the stage is clear for removal for some impediments to a more effective publication culture. Some, not all. The more general problem is the rapidly changing nature of scientific publication, what may be called the concentric waves of publication. That will be the topic of the next article.


[1] Lance Fortnow: Time for Computer Science to Grow Up, in Communications of the ACM, Vol. 52, no. 8, pages 33-35, 2009, available here.

[2] Dagstuhl: Perspectives Workshop: Publication Culture in Computing Research, see here.

[3] Bertrand Meyer: The Modes and Uses of Scientific Publication, article on this blog, 22 November 2011, see here.

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Your IP: does Google care?


A search for my name on Google Scholar [1] shows, at the top of the resulting list, my book Object-Oriented Software Construction [2], with over 7800 citations in the scientific literature. Very nice (thanks, and keep those citations coming!).

That top result is a link to a pirated version [3] of the full content — 1350 pages or so — at an organization in Indonesia, “Institut Teknologi Telkom”, whose logo bears the slogan “Center of Excellence in ICT”. The text has been made available, along with the entire contents of several other software engineering textbooks, in a directory helpfully called “ebooks”, apparently by a user with the initials “kms”. I think I know his full name but attempts at emailing him failed. I wrote a couple of times to the site’s webmaster, who does not respond.

Needless to say, the work is copyrighted and that online copy is not authorized. (I realize that to some people the very idea of protecting intellectual property is anathema, but I, not they, wrote the book, and for the time being it is not public property.)

At least Google could avoid directing people to a pirated text as the first answer to a query about my publications. I was able to to bring the issue to the attention of someone at Google; that result is already something of a miracle, as anyone who tries to interact with a human being regarding a Google-related problem can testify. The history of that interaction, which was initially about something else, might serve as the subject for another article. The person refused to do anything and pointed me to an online tool [4] for removing search results.

Navigating the tool proved to be an obstacle course, starting with the absence of Google Scholar among the Google products listed (I inquired and was told to use “Web Search”). Interestingly, to use this service, you have to be logged in as a Gmail user; I do have a gmail account, but I know several people, including a famous computer scientist, who refuse to open one out of fear for their privacy. Think of the plight of someone who has a complaint against Google results affecting his privacy, and to lodge that complaint must first register as a Google user! I did not have that problem but had to navigate the obstacle course. (It includes one of those “Captchas” that are so good at preventing automatic tools from deciphering the words that humans can’t read them either — I have pretty good eyesight and still I had to try five times. Fodder for yet another article.) But I succeeded, sent my request, and got an automatic acknowledgement. Then…

Then nothing. No answer. The search results remain the same. No one seems to care.

Here is a little thought experiment. Imagine you violated Google’s IP, for example by posting some Google proprietary code on your Web page. Now I have a hunch that they would respond faster. Much faster. This is all pure speculation of course, and I am not advising anyone to try the experiment for real. Pure speculation.

In the meantime, maybe I can at least use the opportunity for some self-promotion. The book is actually pretty good, I think. You can buy it at Amazon [5] for $97.40, a bit less for a used copy. But why pay? Google invites you to read it for free. Just follow the link they obligingly provide at [1].


[1] Result of a search for author:”b meyer” on Google Scholar: see here.

[2] Bertrand Meyer: Object-Oriented Software Construction, 2nd edition, Prentice Hall, 1997. See the book’s page at Eiffel Software here and the Wikipedia entry here. Note that either would be appropriate for Google Scholar to identify the book.

[3] Bootlegged version of [1] here.

[4] Google: “Removing content from Google”, page available here.

[5] Amazon book page for [1]: here.

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Publication list


I have updated my publication list [1] to include recently published and accepted papers, and some ongoing work. Most of the papers are collaborative, reflecting the work of our ETH and ITMO groups on verification, concurrency and methodology.



[1] Publication list, available here (in various formats).

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New LASER proceedings

Springer has just published in the tutorial sub-series of Lecture Notes in Computer Science a new proceedings volume for the LASER summer school [1]. The five chapters are notes from the 2008, 2009 and 2010 schools (a previous volume [2] covered earlier schools). The themes range over search-based software engineering (Mark Harman and colleagues), replication of software engineering experiments (Natalia Juristo and Omar Gómez), integration of testing and formal analysis (Mauro Pezzè and colleagues), and, in two papers by our ETH group, Is branch coverage a good measure of testing effectiveness (with Yi Wei and Manuel Oriol — answer: not really!) and a formal reference for SCOOP (with Benjamin Morandi and Sebastian Nanz).

The idea of these LASER tutorial books — which are now a tradition, with the volume from the 2011 school currently in preparation — is to collect material from the presentations at the summer school, prepared by the lecturers themselves, sometimes in collaboration with some of the participants. Reading them is not quite as fun as attending the school, but it gives an idea.

The 2012 school is in full preparation, on the theme of “Advanced Languages for Software Engineering” and with once again an exceptional roster of speakers, or should I say an exceptional roster of exceptional speakers: Guido van Rossum (Python), Ivar Jacobson (from UML to Semat), Simon Peyton-Jones (Haskell), Roberto Ierusalimschy (Lua), Martin Odersky (Scala), Andrei Alexandrescu (C++ and D),Erik Meijer (C# and LINQ), plus me on the design and evolution of Eiffel.

The preparation of LASER 2012 is under way, with registration now open [3]; the school will take place from Sept. 2 to Sept. 8 and, like its predecessors, in the wonderful setting on the island of Elba, off the coast of Tuscany, with a very dense technical program but time for enjoying the beach, the amenities of a 4-star hotel and the many treasures of the island. On the other hand not everyone likes Italy, the sun, the Mediterranean etc.; that’s fine too, you can wait for the 2013 proceedings.


[1] Bertrand Meyer and Martin Nordio (eds): Empirical Software Engineering and Verification, International Summer Schools LASER 2008-2010, Elba Island, Italy, Revised Tutorial Lectures, Springer Verlag, Lecture Notes in Computer Science 7007, Springer-Verlag, 2012, see here.

[2] Peter Müller (ed.): Advanced Lectures on Software Engineering, LASER Summer School 2007-2008, Springer Verlag, Lecture Notes in Computer Science 7007, Springer-Verlag, 2012, see here.

[3] LASER summer school information and registration form,

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TOOLS 2012, “The Triumph of Objects”, Prague in May: Call for Workshops

Workshop proposals are invited for TOOLS 2012, The Triumph of, to be held in Prague May 28 to June 1. TOOLS is a federated set of conferences:

  • TOOLS EUROPE 2012: 50th International Conference on Objects, Models, Components, Patterns.
  • ICMT 2012: 5th International Conference on Model Transformation.
  • Software Composition 2012: 10th International Conference.
  • TAP 2012: 6th International Conference on Tests And Proofs.
  • MSEPT 2012: International Conference on Multicore Software Engineering, Performance, and Tools.

Workshops, which are normally one- or two-day long, provide organizers and participants with an opportunity to exchange opinions, advance ideas, and discuss preliminary results on current topics. The focus can be on in-depth research topics related to the themes of the TOOLS conferences, on best practices, on applications and industrial issues, or on some combination of these.


Submission proposal implies the organizers’ commitment to organize and lead the workshop personally if it is accepted. The proposal should include:

  •  Workshop title.
  • Names and short bio of organizers .
  • Proposed duration.
  •  Summary of the topics, goals and contents (guideline: 500 words).
  •  Brief description of the audience and community to which the workshop is targeted.
  • Plans for publication if any.
  • Tentative Call for Papers.

Acceptance criteria are:

  • Organizers’ track record and ability to lead a successful workshop.
  •  Potential to advance the state of the art.
  • Relevance of topics and contents to the topics of the TOOLS federated conferences.
  •  Timeliness and interest to a sufficiently large community.

Please send the proposals to me (Bertrand.Meyer AT, with a Subject header including the words “TOOLS WORKSHOP“. Feel free to contact me if you have any question.


  •  Workshop proposal submission deadline: 17 February 2012.
  • Notification of acceptance or rejection: as promptly as possible and no later than February 24.
  • Workshops: 28 May to 1 June 2012.


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Various interviews

Over the past few months I have given a few interviews to Russian news outlets on technology- and software-related issues. Here are the links I have.

In September, Mikhail Saprykin interviewed me [1] for Kommersant (the main Russian business daily) on a question that worries everyone in technology and academia: the brain drain.

In early November, at the SECR conference in Moscow where I gave a keynote [2], Natalia Dubova from Open Systems, the principal applied publication on software issues (which published translations of many of my articles over the years), interviewed me on the theme of software reliability and Eiffel [3].

On the same occasion, Internet University, which recently published the translation [4] of my introductory programming textbook Touch of Class [5], recorded a video conversation [6] between Prof. Vladimir Billig from Tver Technical University and me. Vladimir (pictured here a few weeks later)

Vladimir Billig

is the book’s translator; he had already translated the second edition of Object-Oriented Software Construction.

On December 19 I was interviewed with Dmitry Grishin, head of — the biggest Russian internet companies — by Alexander Belanovskiy at the radio station “Echo Moskvy” in Moscow, for Echonet, the station’s technology program. The interview will air, I was told, on January 15.

On the occasion of a talk I gave on December 19 at the Technical University of Tver, a historic city at the junction of the Volga (appearing on the far-right in the picture) and the Tverska,

Tver, November 2011I was interviewed on two separate TV stations (one of them Russia 1); I didn’t get to see the broadcasts, but if anyone finds them on the Web I will be grateful for the links.

Tver house

Tver church


[1] Interview by Mikhail Saprykin in Kommersant, 20 September 2011, available here.

[2] Keynote at Software Engineering Conference Russia, available here.

[3] Interview by Natalia Dubova in Otkrytye Systemy (Open Systems), vol. 10, no. 21, December 2011, available here.

[4] Potchustvuj Klass: translation by Vladimir Billig of Touch of Class [5], book page available here.

[5] Bertrand Meyer: Touch of Class: Learning to Program Well, Using Objects and Contracts, Springer Verlag, 2009, book page available here.

[6] Video interview with Vladimir Billig, available here.

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