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Today I learned that Ernie Esser passed away on March 8th, 2015 at age 34. Ernie was a PostDoc at UBC, Vancouver (PhD from UCLA) and worked in applied mathematics, especially imaging, optimization and inverse problems. I can’t say that I knew him very well – but we were in the similar research communities and I remember sitting with him in restaurants and chatting at several occasions (e.g. in Vancouver and Hong Kong…) and I remember him as a perticularly nice guy. Also I followed his work and it frequently happened that I found papers by him thinking “ok, that’s solved” crossing a problem from the list of thing I would have liked to work on.

I am seriously shocked to learn that he died from pneumonia, especially at his young age. There is a obituary weblog here and I am glad that his workgroup did not only set up this page but also plans to do a scientific event to recognize his work.

A quick post to keep track of several things:

• Christian Leonard  has lecture notes on convex optimization with an application to optimal transport on his website.
• The paper Variational Properties of Value Functions by  Aravkin, Burke, and Friedlander discuss how the value of minimization problems like $\min \rho(Ax-b)\quad \mbox{s.t}\quad \phi(x)\leq tau$ depend on $\tau$ and $\latex b$. In inverse problems, the value function seems to contain important information on the the regularization process and hence, the results in this paper maybe helpful in designing and analyzing parameter choice rules.
• The paper Accelerated and Inexact Forward-Backward Algorithms by Villa,Salzo, Baldassarre, and Verri looks like an interesting development in the fiel of splitting methods.
• The paper  Consistency of the posterior distribution in generalized linear inverse problems by Natalia Bochkina is another contribution on “probabilitic inverse problems” where one does not only try to infer a regularized solution to an ill posed problems but also how the uncertainty in the data in propagated through the regularization process.

This is the last post in a series of posts (which was not intended to be a series). The series started with this post in which I reported some experience with job interviews I had in spring last year, and continued with this post which told what happened afterwards. The story ended with the paragraph “Now the final steps will be: Preparation of the next list of wishes, negotiations to stay and finally, the most difficult part, forming a well-founded decision.” That was about eleven month ago and was not totally wrong. Here is what happened then:

1. The Bleibeverhandlung

The Bleibeverhandlung (the negotiations to stay) is in principle similar to the negotiations with other universities. But there are important differences: The first one is due to the fact that there has been no official committee of the department involved so far and hence, the department has to form an opinion on how much they want to keep you. As far as I know this usually happens in an informal way and can be very different in different places and also the dean (or, in my case, the “speaker of the department”) may handle this in its own way. Also, you will not be involved in this step in any way (I think). The amount of support you get is crucial for the next steps. The department has to report its opinion to the dean (who is basically in control of the money here) and the dean has to decide about a strategy how to keep you (if your support is strong enough). Again, this is very different in different cases. Also, I do not know too much about this process, but at least there will be some communication between the dean and the president (or their offices). But after this procedure, the next steps of negotiations are basically the same as before: First negotiations with the dean, then with the president. Again, the first negotiation is somehow more important as many things are handled by the dean. In my case there was the question on which kind of position the department could keep me and how it could be arranged to fill this position with me. I have been Juniorprofessor (basically equal to assistant professor) and according to German law, there is not way of promotion to the “next level”. The university had to find an “open position for a professor”. But there was such a position (which I knew before since I had a tenure track position). The next obstruction was that, again according to German law, there usually has to be an official public announcement if such a position is to be filled. Consequently, anyone who is qualified could apply and should have a positive probability to get the job. However, I learned that my state has the possibility to fill a position without public announcement and it was part of my offer that my university “offered to start the initiation of this procedure”. It is somehow difficult to translate but the university could not even offer to initiate this “filling without public announcement” because this is something on which several committees has to agree.

2. The decision

Well, I had the official offer of my university pretty quick after negotiations. Basically, it was on par with the other offers (slightly better in some respects, slightly worse in others – but clearly no clear winner). The only caveat was, that there was no guarantee that I could get a permanent position because this depended on the decision of more committees. However, I had a formal statement that the president and the dean would initiate and support the procedure. Moreover, colleagues told me that my university had done a great job in keeping its promises in similar respects.

So, the decision was not easy. However, I decided not to play “ping-pong” with the other universities (which could be possible – but I can not tell you how that works) and to decide on basis of the facts I had after one round of negotiations. It was a tough and close decision which I do not comment in more detail here. But I decided to stay at TU Braunschweig.

3. Another application

End of the story – indeed a happy end for me. The procedure was quite slow – but as far as I’ve heard all the people who have been involved did their best to make the procedure as quick as possible and I am very thankful for the effort and support of many people. It is just an awfully complicated procedure to appoint a professor in Germany which consists of many steps and many people and committees are involved…

This time I have something which is very specific for the German academic system and it seems to me that writing in German is more appropriate here.

Die Berufung von Professoren ist ein aufwändiges und langwieriges Unterfangen. Es gibt viele Regeln zu beachten und viele Meinungen und Daten fließen ein. Insgesamt soll “der/die beste Kandidat/in” die Stelle bekommen. Die Entscheidung basiert am Ende auf dem Votum der Kommission die sich ihre Meinung auf Grund der Eckdaten der Bewerbung und des Lebenslaufes, des persönlichen Eindrucks bei der Vorstellung und auf dem Votum externer Gutachter bildet. Das alles kostet viel Zeit und Arbeit. Außerdem kann das ganze Verfahren schnell unter den Verdacht kommen, dass persönliche Beziehungen eine zu große Rolle spielen könnten und dass am Ende nicht immer “der/die Beste” genommen wird (obwohl es umfangreiche Regeln zum Ausschluss von Befangenheit gibt). Man stelle sich vor, es gäbe eine zentrale Stelle, die mit viel Aufwand und geschultem Personal Daten über Nachwuchswissenschaftler sammelt:

• Wer hat was publiziert? Wer wird wie oft zitiert?
• Wer trägt auf welchen Konferenzen und Workshops vor? Und wer wird von wem eingeladen?
• Was denken die führenden Köpfe, wer die großen Nachwuchstalente sind? Was denken die Nachwuchskräfte über sich gegenseitig?
• Wer hat wieviel Drittmittel eingeworben? Wer hat welche Kooperationen initiiert und welche Patente angemeldet?

All das lässt sich durch eine zentrale und unabhängige Stelle viel effizienter und auch viel objektiver erheben. Eine Berufungskommission könnte sich dann einfach und schnell eine fundierte Meinung bilden. Eine einfache Datenbankanfrage an die zentrale Stelle würde sofort eine Auskunft liefern, wer von den Kandidaten am besten da steht und die Auswahl aus den oft über fünfzig Bewerbungen wäre kaum noch Arbeit…

Würde das Verfahren funktionieren? Würde irgendjemand das Verfahren akzeptieren? Die Antwort auf diese rhetorischen Fragen fällt eindeutig aus: Eine solche zentrale Stelle wäre völliger Schwachsinn und die Informationen, die sie liefern könnte wären nutzlos. Einerseits sind die Kriterien sicherlich nicht gut gewählt: Publikationen in der “wissenschaftlichen Vanity-Press” zählen gleich viel wie ein Artikel in den Annals? Was ist mit interdisziplinären Arbeiten, die in leicht “fachfremnden” Zeitschriften erscheinen? Einladungen auf Konferenzen lassen sich durch Gegeneinladung erschleichen. Eine gute Reputation bekomme ich nur, wenn ich mich Gut-Freund mit den wichtigen Leuten mache – gute “Netzwerker” haben da natürlich einfacher, als “stille Wasser”. Man könnte natürlich versuchen, bei den Kriterien nachzubessern: Wir beziehen die Reputation einer Zeitschrift mit ein! Wir checken “Gegeneinladungen” und rechnen sie wieder heraus! Wir beziehen auch Zeitschriften in “angrenzenden Feldern” mit ein! Man merkt schnell, dass auch das Nachbessern zum Scheitern verurteilt ist: Wer legt denn die Reputation einer Zeitschrift fest? Gegeneinladungen sind nicht immer ein Zeichen von Gemauschel, sondern oft ganz natürlich und Ausdruck einer Kooperation. Welche Felder grenzen denn an und wo wird dann die Grenze gezogen?

Außerdem ist eine solche zentrale Stelle auch fundamental in Frage zu stellen: Ist es überhaupt machbar, Kandidaten neutral und objektiv zu Bewerten? Und was soll “objektiv” bedeuten, wenn doch jeder Lebenslauf verschieden und die Anforderungen an jede Stelle und an jeder Uni verschieden sind? Eine anerkannte, allgemeingültige Methode, um Kandidaten gegeneinander abzuwägen gibt es nicht. Eine standardisierte, zahlenbasierte Bewertung von Personen ist absurd. Eine derart komplexe Thematik lässt sich nicht durch ein automatisches Verfahren und einfach in Zahlen abbilden. Vom ethischen Aspekt ganz zu schweigen…

Schon mal was vom CHE Uni-Ranking gehört?

Geometry, Imaging and Computing

A short note to myself: There is the new journal “Geometry, Imaging and Computing” published by International Press which looks interesting for papers inbetween computer vision and computer graphics.

I have an open position for a Scientific Assistant/PhD student available. The salary is according to TV-L EG 13. (Don’t know what that means? Have a look here.). The position starts at 01.09.2013 (earlier start is possible) and is initially limited to two years; further extension is possible and for a PhD student, at least three years are planned.

Candidates should

• have a degree (Masters or Diploma) in mathematics above average,
• have very good knowledge in numerical mathematics and functional analysis,
• have good knowledge in scientific computing or optimization,
• know German well and
• have strong interest in applied mathematics. Also, bring a high commitment for scientific research.

The responsibilities include

• participation in teaching and
• independent but supervised research in field of applied mathematics (especially mathematical imaging and inverse problems).

Please send applications including CV, copies of certificates and letters of recommendation (if any) in electronic form directly to me. Deadline is the 30.06.2013.

If you would like to post the job advertisement at you bulletin board, here’s the pdf file.

Although I think that most readers of this blog also follow “What’s new” , I could not help to share the most recent post there also here. Yesterday, Terry Tao featured a guest post by nobody less than the present president of the International Mathematical Union (IMU), Ingrid Daubechies.

The post is “Planning for the World Digital Mathematical Library” and, in a nutshell, Ingrid Daubechies present the plans of the IMU to build a new online digital library for mathematics and asks the math community for input to make this library most useful using the best of the available technology. Go and read the post. Then start thinking about how you work with mathematical literature (How do you find it? How do you use it? Do you archive it for yourself? Do you rely on other online databases? How do you communicate about articles and books with others?). This quickly generates ideas for the mathematical library: Errata could be tracked automatically, one could have a way to archive notes for articles you read directly linked to the article/book, these notes could be public, semi-public or shared within some community, the library could be used to have reliable and unified identifiers for bibliographies (no more taking care or messy merging of bibtex-files),… So go ahead and provide your input – this can be big.

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