My field of expertise is combinatorial optimization. In the recent years, I am in particular interested in the use of semidefinite programming to design efficient approximations for hard combinatorial problems (graph coloring, max-cut, etc.), and more generally, for polynomial optimization problems, where objective and constraints are polynomial functions and algorithms can be developed using algebraic techniques.

For further information, please refer to my webpage at CWI

Part-time Full Professor at the Department of Econometrics and Operations Research, Tilburg School of Economics and Management, September 2009- Present.

Management Team Member at CWI, 2016 to 2021.

Leader of the research group Networks and Optimization at CWI, 2005 to 2016.

Researcher at Centrum Wiskunde & Informatica (CWI), Amsterdam,1997.

Research Fellow of the Von Humboldt Foundation at the Institute of Discrete Mathematics and Operations Research in Bonn, Germany, August 1990 to February 1992.

Researcher at CNRS (Paris, France), with affiliation with Universite Paris Dauphine between 1988-1992 and at Ecole Normale Superieure  between 1992-1997.

Research Engineer at CNET (Centre National d'Etudes des Telecommunications, Paris, France),1986 to 1988.

Guest Researcher at New York University, 1985 to 1986.

Luis Felipe Vargas, PhD student at CWI (with J. Vera as co-supervisor). Planned defense on 3 November 2023. Title: Sum-of-Squares Representations for Copositive Matrices and Independent Sets in Graphs.

Andries Steenkamp, PhD student at CWI (with E. de Klerk as co-supervisor). Planned defense on 30 October 2023. Title: Polynomial optimization: matrix factorization ranks, portfolio selection, and queuing theory.

Daniel Brosch, PhD student at Tilburg U. (as co-supervisor, with E. de Klerk as supervisor). PhD defense at Tilburg University on 19 October 2022. PhD thesis: Symmetry Reduction in Convex Optimization with Applications in Combinatorics.

Lucas Slot, PhD student at CWI (with E. de Klerk as co-supervisor). Defense on 30 September 2022 at Tilburg University (Cum Laude). PhD thesis: Asymptotic Analysis of Semidefinite Bounds for Polynomial Optimization and Independent Sets in Geometric Hypergraphs.

Joran van Apeldoorn, PhD student at CWI (as co-supervisor; R. de Wolf as supervisor). Defense at UvA on 6 February 2020. PhD thesis: A quantum view on convex optimization.

Sander Gribling, PhD student at CWI (with R. de Wolf as co-supervisor). Defense on 30 September 2019 at Tilburg University. PhD thesis: Applications of optimization to factorization ranks and quantum information theory.

Matteo Seminaroti, PhD student at CWI (with R. Sotirov as co-supervisor). Defense on 2 December 2016 at Tilburg University. PhD thesis: Combinatorial algorithms for the seriation problem.

T. Piovesan, PhD student at CWI (with H. Buhrman as co-supervisor). Defense at University of Amsterdam on 27 October 2016. PhD thesis: Quantum entanglement: insights via graph parameters and conic optimization.

Z. Sun, PhD student at Tilburg University (with E. de Klerk as co-supervisor). Defense on 29 June 2015 at Tilburg University. PhD thesis: Polynomial Optimization: Error Analysis and Applications.

A. Varvitsiotis, PhD student at CWI. Defense on  25 November 2013 at Tilburg University. PhD thesis: Combinatorial Conditions for Low Rank Solutions to Semidefinite Programs.

N. Gvozdenović, PhD student at CWI (with A. Schrijver as co-supervisor). Defense on 10 April 2008 at UvA. PhD thesis: Approximating the Stability Number and the Chromatic Number of a Graph via Semidefinite Programming.

Regular Course: "Orientation Research Topics in OR"

Bi-Annual Basis: 

• "Networks and Semidefinite Programming", within  LNMB:https://www.lnmb.nl/pages/courses/phdcourses/
• "Semidefinite Optimization", within Mastermath https://elo.mastermath.nl/