n this issue of IEEE Control Systems Magazine (CSM), we I speak with 2014 IEEE Control Systems Society President » PEOPLE IN CONTROL We also speak with six other IEEE Fellows in the control systems field. Vincent Blondel is professor of applied mathematics at the Louvain School of Engineering at the Université catholique de Louvain (Louvain-la-Neuve, ) and dean of engineering at the École Polytechnique de Louvain. He received an engi- neering degree, a degree in philosophy, and a Ph.D. in applied

mathematics from the Université catholique de Louvain and an M.Sc. in pure mathematics from Imperial College , United Kingdom. He has also completed a master’s thesis at the Institut National Polytechnique de (France). He is a research affiliate at the Massachusetts Institute of Technol-ogy (MIT), where he was visiting professor and Fulbright fel-low in 2005–2006 and 2010–2011. His major current research interests lie in several areas of mathematical control theory, theoretical computer science, and network science.

VINCENT BLONDEL I found these papers difficult to read to state (“under what conditions are Q. How did your education and and far from my attraction to pure three linear systems stabilizable by the early career lead to your interest in mathematics. I then came across the same controller?”), the problem had the control field? very nice book Control System Synthesis already been open for some time (it is Vincent: For many years I felt that by M. Vidyasagar. I could only under- actually still open), and the problem my initial choice to study engineer- stand its contents up to Chapter 6, but was mathematically clear. This was ing rather than mathematics had that chapter contained the description the perfect combination for my pure been a mistake. As a student, I read of a clearly stated problem: simulta- mathematics aspirations at that time, a lot on mathematics and on the his- neous stabilization of linear systems. and I decided to make this the subject tory of mathematics. I was fascinated This was a problem that was easy of my Ph.D. thesis. by works such as “A Mathematician’s Apology” by Cambridge number the- orist G.H. Hardy. Hardy would write things such as: “The mathematician’s patterns, like the painter’s or the poet’s must be beautiful; the ideas like the colors or the words, must fit together in a harmonious way. Beauty is the first test: there is no permanent place in the world for ugly mathematics.” I would read this and feel thrilled! After my engineering studies, I went on for a master of science in mathematics at Imperial College in London and then completed a Ph.D. in control. For my Ph.D., I was first given papers to read in H-infinity control. This was the fancy topic at the time.

Digital Object Identifier 10.1109/MCS.2013.2279451 Date of publication: 14 November 2013 Vincent Blondel in good company at the Media Lab at MIT.

28 IEEE CONTROL SYSTEMS MAGAZINE » DECEMBER 2013 This was a quarter century ago. I no longer read Hardy and I now Profile of Vincent Blondel: see things very differently—to the r Current position: professor of applied mathematics and dean of engineering, point that I even disagree with some Louvain School of Engineering, Université catholique de Louvain, Belgium. of the statements made by Hardy. A r Visiting and research positions: Petar Kokotovic Distinguished Visiting Profes- couple of years ago, the king of Bel- sor, University California, Santa Barbara (2012–2013); visiting professor, Mas- gium, HRH King Albert II, was on a sachusetts Institute of Technology, Cambridge (2005–2006 and 2010–2011). state visit in India. I had been invited r Contact information: Avenue Georges Lemaître 4, boîte L4.05.01, B-1348 with a few other academics to be part Louvain-la-Neuve, Belgium, +32 10 47 23 81, [email protected], of the royal delegation. At the end of http://perso.uclouvain.be/vincent.blondel/. the first day, I was introduced to the r Notable awards: SIAM Triennial Prize on Control and Systems Theory, 2001; king for a brief discussion. The king Fulbright Scholar, U.S. State Department, 2005; IEEE Antonio Ruberti Prize asked me what my research area was, in Systems and Control, 2006; IEEE Fellow, 2012. and I replied “control theory and applied mathematics.” The king, not a scientist by training, then asked “So, tion and Decision Systems (LIDS) that works: Friends, Money, and Bytes” Mr. Blondel, what is control theory continues to this day. This collabora- by Mung Chiang from Princeton and applied mathematics?” I quickly tion extended to include many more University (on coursera), and we had figured out it was best not to start colleagues and friends at LIDS and weekly discussions about the course explaining Maxwell’s governor or is one of the best things that has hap- in class. MOOC courses offer visibil- Routh’s test, but there were plenty of pened in my scientific life. For about ity to scientific disciplines in ways other examples from applied math- a decade, we have analyzed the com- that may be even more important ematics to choose from. At the end putational complexity of control prob- than textbooks. I feel that a good of the conversation, the king told me: lems and have shown many of them to MOOC introductory course in con- “Mr. Blondel, applied mathematics be intractable. This interest drew me trol on one of the most prominent are very important.” I believe the king to hybrid systems, and in particular MOOCs platforms would be benefi- was right, and I am now really happy to switching linear systems and long cial to the entire control community. that I chose engineering. products of matrices. And then by I have had my university join the analytical continuation I reached net- edX platform but I do not see any Q. What are some of your research work problems, then the analysis of control courses available yet. interests? large network data sets as a proxy for Vincent: Frank Callier, a Belgian human behavior. Still, in continuation, Q. You are the coeditor of two books control theorist, had a very personal I am now concerned by privacy ques- on open problems in control. How did and colorful way of describing things. tions. This path illustrates the power you decide to coordinate these books? He once told me he chose his research of analytic continuation; control leads Vincent: These two books are part interest by “analytical continuation.” everywhere! of a larger initiative. I have always (In complex analysis “analytic con- felt that researchers spend too much tinuation” is a technique to extend Q. What courses do you teach relat- time explaining what they have been the domain of a given analytic func- ing to control? Do you have a favorite successful at rather than describing tion). I very much proceed by analytic course? unsolved problems or things that continuation, moving to areas close Vincent: I teach courses in applied they have attempted and that have not enough that I do not have to start mathematics and computer science. worked. I am not advocating describ- everything from scratch and can bring Last year, I taught a course on the ing at length how people fail but I feel some potentially helpful perspectives emerging field of complex networks, that there is much to be learned from but different enough to maintain my for which there are now a few good the genesis of a problem. With this in interest and not hit the same questions textbooks available. For the first time mind, and with the help of my doc- or difficulties again and again. Simul- this year, I tried to flip one of my toral and postdoctoral supervisors taneous stabilization, the topic of my classrooms and had students watch Michel Gevers and Anders Lindquist, Ph.D., was too hard to solve, so I tried lectures online first and then work I first solicited open problems and proving that it was a computationally on problem sets and interact in class. major challenges from prominent con- hard. In this way, I became interested This approach is meant to allow the trol theorists (this list was published in the computational complexity of instructor to spend more time inter- in the first issue of the European Journal control problems and started a fruitful acting with students instead of lec- on Control). I then organized a special collaboration with Prof. John Tsitsiklis turing. My students took a MOOC session on open problems in 1995 at the at the MIT Laboratory for Informa- (massive online open course), “Net- Conference on Decision and Control.

DECEMBER 2013 « IEEE CONTROL SYSTEMS MAGAZINE 29 I vividly remember Roger Brockett action but one of the books is freely artistic talents at a high level. I have siting in the front row. For any prob- available on the Web, and some of the not been able to do so but, together lem presented, he would ask: “What problems have generated considerable with my wife, I greatly enjoy spend- application do you have in mind? Is interest and research activity. ing time with our three teenage this mathematics or engineering?” He daughters (ages 13, 15, and 17) and had an authentic interest in the session Q. What are some of your interests with our younger son (age 9), and I but insisted that control theory should and activities outside of your profes- try to figure out how not to regret help solve real problems. This session sional career? this very special time when it will led me to coordinate the publication of Vincent: My coauthor Jakob have passed. I also occasionally play a first book on open problems in con- Stoustrup has this statement on his tennis and travel (and not only to trol (with E. Sontag, M. Vidyasagar, Web page: “This is what I do in my conferences …). and J.C. Willems) and then a second spare time.” When you click on the book (with A. Megretski). I wanted the link you get the response, “Spare Q. Thank you for your comments. books to be freely available on the Web time: what spare time?” I could have Vincent: Many thanks for asking! I and to be “living books,” allowing the something similar on my Web page! love this section. There is no Web-like collaborative addition of comments, I admire colleagues who are able to analytics for magazines but if there was, remarks, references, etc. The initiative cultivate, in parallel to an accom- I am convinced this section would have a never quite reached that level of inter- plished scientific career, athletic or high PageRank!

30 IEEE CONTROL SYSTEMS MAGAZINE » DECEMBER 2013