Kees Roos and Jean-Philippe Vial win the 2011 INFORMS Optimization Society Khachiyan Prize

Jon Lee (left), Jean-Philippe Vial, Kees Roos, and George Nemhauser.


The 2011 recipients of the INFORMS Optimization Society Khachiyan Prize, for their remarkable life-time achievements in the area of optimization, are Kees Roos, Emeritus Professor of Delft University of Technology, The Netherlands, and Jean-Philippe Vial, Emeritus Professor of the University of Geneva, Switzerland.

During their remarkable careers, Kees Roos and Jean-Philippe Vial have grown to be among the world's foremost experts in the area of continuous optimization, with main interest in the fundamental problems of linear programming. Through their research, training and service contributions, they are among the most recognized members of the INFORMS community. Kees Roos and Jean-Philippe Vial played a key role in the development of Interior Point Methods (IPMs) worldwide, and in particular in Europe. Soon after Leonid Khachiyan proved the polynomial-time solvability of LP and Karmarkar introduced his projective method, Roos and Vial started their long term and high impact collaboration on IPMs. Their first joint publication, "A polynomial method of approximate centers for linear programming," published in Mathematical Programming, contains a very elegant and simple polynomial-time IPM, that still today yields the best complexity bound for solving linear optimization problems. This paper has inspired many (young) researchers. They continued to play a key role in the developments of IPMs and not only published numerous impactful papers on IPMs together, but were also able to set up strong and productive research groups on IPMs. Roos and Vial supervised many PhD students, postdocs and visitors on IPMs, who later become highly successful in the area of optimization, both in practice and academia. Their collaboration also resulted in a very influential book on IPMs: "Theory and Algorithms for Linear Optimization: An Interior Point Approach" (with co-author Tamás Terlaky) in 1997, with a new edition by Springer in 2006. This seminal book is introducing generations of researchers to IPMs. 
Both Roos and Vial have carried out important applied optimization projects with high scientific and societal impact. Kees Roos recently carried out an important project for the Dutch government on "Optimizing dike heights in the Netherlands." Jean-Philippe Vial developed appropriate tools for several large companies for handling uncertainty in large economic, energy and climate models for the assessment of global environmental policies.

Kees Roos has published more than one hundred papers in international peer-reviewed journals. He has also co-authored another important book, in which a new paradigm of IPMs, called "self-regularity," is described. ("Self-Regularity. A New Paradigm for Primal-Dual Interior-Point Algorithms," Princeton University Press, 2002). He is a Fellow of EUROPT, the European Working Group on Continuous Optimization.

Jean-Philippe Vial has published over one hundred papers in premier international OR journals. He served as President of the Mathematical Programming Society in 1998-2001. He has also been an associate editor of Management Science, and edited several influential proceedings.

Selection committee

George Nemhauser (Chair), Yurii Nesterov, Lex Schrijver, Tamás Terlaky