research

Research Interests

• Combinatorial Optimization

• Mathematical Programming

• Semidefinite Programming

• Integer Programming

• Integer Semidefinite Programming

• Mixed Integer Programming

• Interior Point Methods and ADMM

• Branch and Bound Algorithms

• Applications of Optimization

PhD Students

• Mathijs Barkel, MSc (September 2023 - )

• Lennart Sinjorgo, MSc (September 2022 - )

• Fatih Burak Akcay, MSc (September 2022 - )

• Tijn W.A. Fleuren, MSc (September 2020 - )

• Frank de Meijer, MSc (September 2019 - )

• Dr. Hao Hu (September 2016 - September 2019)

• Dr. Olga Kuryatnikova (September 2016 - September 2019) , Co-supervisor: Prof. Juan Vera

• Dr. Uwe Truetsch (January 2011 - October 2014),  Co-supervisor: Prof. Etienne de Klerk

• Dr. Ning Ma (September 2010 - September 2014),  Co-supervisor: Prof. Jalal Ashayeri

• Dr. Chris Fricke (August 2006, Melbourne), Co-supervisors: Prof. Natashia Boland and Prof. Garry Froyland

Postdoctorands

• Dr Elizabeth Gaar (February - March 2019)

• Dr Marianna Nagy ,  Co-supervisor: Prof. Etienne de Klerk (September 2010 - August 2011)

• Dr Yuichi Takano (April-October 2010)

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MATLAB codes

Improved reverse Cuthill-McKee algorithm for symmetric graphs, see below.

The  q-random coordinate constrained algorithms: q-RCC1 and q-RCC2, see also below. 

A Library of structured SDP instances

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Papers Under Review

• Cuts and semidefinite liftings for the complex cut polytope, with Lennart Sinjorgo and Miguel Anjos, Preprint, 2024.

• Exploiting Symmetries in Optimal Quantum Circuit Design, with Frank de Meijer, Dion Gijswijt, Preprint 2024. 

• On convergence of a q-random coordinate constrained algorithm for non-convex problems, with Alireza Ghaffari-Hadigheh and Lennart Sinjorgo, preprint 2022.  

• Tactical Production Planning and Strategic Buffer Placement in the High-Tech Manufacturing Industry, with Tijn Fleuren, Yasemin Merzifonluoglu and M. Hendriks, Preprint 2022.

Publications

• The Chvátal-Gomory Procedure for Integer SDPs with Applications in Combinatorial Optimization, 

with Frank de Meijer, Mathematical Programming, accepted, 2024.

• The quadratic minimum spanning tree problem: lower bounds via extended formulations, 

with Z. Verchere, Vietnam Journal of Mathematics, accepted, 2024. SV test instances and feasible solutions for the QMSTP. 

• On integrality in semidefinite programming for discrete optimization, 

    with Frank de Meijer,  SIAM Journal on Optimization, https://doi.org/10.1137/23M1580905 , 2023.

• On solving the MAX-SAT using sum of squares, 

    with Lennart Sinjorgo, INFORMS Journal on Computing, accepted, https://doi.org/10.1287/ijoc.2023.0036,  2023.

• Partitioning through projections: strong SDP bounds for large graph partition problems, 

    with Frank de Meijer, Angelika Wiegele and Shudian Zhao, Computers and OR, 151, 2023.

• Facial Reduction for Symmetry Reduced Semidefinite Doubly Nonnegative Programs, 

    with Hao Hu and Henry Wolkowicz,  Mathematical Programming, 200:475--529, 2023.  

• On the generalized $\vartheta$-number and related problems for highly symmetric graphs, 

    with Lennart Sinjorgo,  SIAM Journal on Optimization, 32(2), 1344-1378, 2022.

• Mathematical Programming Models and Exact Algorithms for QUBO,   

with Abraham P. Punnen,  In A.P. Punnen (ed.) Quadratic Unconstrained Binary Optimization Problem: Theory, Algorithms, and Applications, 

chapter 6,  p.139 -185, Springer, 2022.

• The maximum k-colorable subgraph problem and related problems,

with Olga Kuryatnikova and Juan Vera, INFORMS Journal on Computing, 34(1): 656--669 2022.

• SDP-based bounds for the Quadratic Cycle Cover Problem via cutting plane augmented Lagrangian methods and reinforcement learning,

with Frank  de Meijer, INFORMS Journal on Computing, 33(4):1262--1276, 2021. 

received Meritorious Paper Award, INFORMS Journal on Computing

• Lower Bounds for the Bandwidth Problem,

 with Franz Rendl and Christian Truden,  Computers and Operations Research, 135:105422, 2021.

• The linearization problem of a binary quadratic problem and its applications, 

         with Hao Hu, Annals of Operations Research, 307:229-249, 2021. 

• The Quadratic Cycle Cover Problem: special cases and efficient bounds,

with Frank de Meijer, Journal of Combinatorial Optimization, 39:1096–1128, 2020.

• On solving the quadratic shortest path problem,

with H. Hu, INFORMS Journal on Computing, 32(2), 219-233, 2020.

• On solving the densest k-subgraph problem on large graphs,

Optimization Methods and Software, 35(6), 1160–-1178, 2020.  (to download codes q-RCC1 and q-RCC2, see below.)

• Special cases of the quadratic shortest path problem,

with H. Hu, Journal of Combinatorial Optimization, 35(3): 754–777, 2018.

• The min-cut and vertex separator problem,

with F. Rendl, Computational Optimization and Applications, 69(1):159-187, 2018.

• Graph bisection revisited,

Annals of Operations Research, 265(1): 143–154, 2018.

• New bounds for the max-k-cut and chromatic number of a graph,

with E.R. van Dam, Linear Algebra and its Applications, 488:216--234, 2016.

• A new semidefinite programming relaxation for the quadratic assignment problem and its computational perspectives,

with E. de Klerk and U. Truetsch, INFORMS Journal on Computing, 27(2):378 - 391, 2015.

• Semidefinite programming and eigenvalue bounds for the graph partition problem,

with E.R. van Dam, Mathematical Programming, Ser B, 151(2): 379-404, 2015.

• On bounding the bandwidth of graphs with symmetry,

with E.R. van Dam, INFORMS Journal on Computing, 27(1):75-88, 2015.

• The redesign of a warranty distribution network with recovery processes,

with J. Ashayeri, N. Ma, Transportation Research Part E: Logistics and Transportation Review. 77:184 - 197, 2015

• Supply chain network downsizing with product line pruning using a new demand substitution,

with J. Ashayeri, N. Ma, Journal of the Operational Research Society. 66(10): 1669-1685, 2015.

• Supply Chain Downsizing under Bankruptcy: A Robust Optimization Approach,

with J. Ashayeri, N. Ma, International Journal of Production Economics, 154:1–15, 2014.

• An efficient semidefinite programming relaxation for the graph partition problem,

INFORMS Journal on Computing, 26(1): 16-30, 2014.

• Symmetry in RLT cuts for the quadratic assignment and standard quadratic optimization problems,

with E. de Klerk, M. Nagy, U. Truetsch, European Journal of Operational Research, 233(3): 488-499, 2014.

• Multi-start Approach for an Integer Determinant Maximization Problem,

with T. Terlaky, Optimization, 62(1), 101-114, 2013.

• On semidefinite programming bounds for graph bandwidth,

with E. de Klerk, M. Nagy, Optimization Methods and Software, 28(3), 485-500, 2013.

• On semidefinite programming relaxations of maximum k-section,

with E. de Klerk, D. Pasechnik, C. Dobre, Mathematical Programming B, 136(2):253-278, 2012.

• Clique-based Facets for the Precedence Constrained Knapsack Problem,

with N. Boland, A. Bley, C. Fricke, G. Froyland, Mathematical Programming A, 133(1):481-511, 2012.

• Improved Semidefinite Programming Bounds for Quadratic Assignment Problems with Suitable Symmetry,

with E. de Klerk, Mathematical Programming A, 133(1):75--91, 2012.

• A Polynomial Optimization Approach to Constant Rebalanced Portfolio Selection,

with Yuichi Takano, Computational Optimization and Applications, 52(3):645-666, 2012.

• SDP relaxations for some combinatorial optimization problems,

In M.F. Anjos & J.B. Lasserre (Eds.), Handbook of Semidefinite, Conic and Polynomial Optimization:

Theory, Algorithms, Software and Applications, 795--820, 2012.

• Implications of Product Substitutability in Supply Chain Network Downsizing Optimization,

with N. Ma, J. Ashayeri. In: Proceedings of the International Conference on Value Chain Sustainability,

Izmir University of Economics, Turkey, 305-–314, 2012

• Towards global optimization of constant rebalanced portfolio,

with Y. Takano. MET - Medium Econometric Applications, 18(4), 22-28, 2012.

• An Aggregated Optimization Model for Multi-Head SMD Placements,

with J. Ashayeri, N. Ma, Computers and Industrial Engineering, 60(1):99-105, 2011.

• Matrix-Lifting SDP for Detection in Multiple Antenna Systems,

with A. Mobasher, A.K. Khandani, IEEE Transactions on Signal Processing, 58(10):5178--5185, 2010.

• Exploiting group symmetry in semidefinite programming relaxations of the quadratic assignment problem,

with E. de Klerk, Mathematical Programming A, 122(2):225--246, 2010.

• A new library of structured semidefinite programming instances,

with E. de Klerk. Optimization Methods and Software, 24(6):959--971, 2009.

• On the Lovász q-number of Almost Regular Graphs with Application to Erdös-Rényi Graphs,

with E. de Klerk, M.W. Newman, D. Pasechnik. European Journal of Combinatorics, 30:879-888, 2009.

• Exploiting group symmetry in truss topology optimization,

with Y. Bai, E. de Klerk, D.V. Pasechnik, Optimization and Engineering, 10(3):331-349, 2009.

• On semidefinite programming relaxations of the traveling salesman problem,

with E. de Klerk, D.V. Pasechnik, SIAM J. Optim. 19(4):1559-1573, 2008.

• A Near Maximum Likelihood Decoding Algorithm for MIMO Systems Based on Semidefinite Programming,

with A. Mobasher, M. Taherzadeh, A.K. Khandani, IEEE Trans. on Info. Theory, 53(11): 3869-3886, 2007.

• When mathematics meets a real life: The Quadratic assignment Problem. Defacto, 4:34-37, 2007.

• Magnetic Resonance Tissue Density Estimation using Optimal SSFP Pulse-Sequence Design ,

with C. Anand, T. Terlaky, Z. Zheng, Optimization and Engineering, 8(2):215-238, 2007.

• Bounds for the Quadratic Assignment Problem Using the Bundle Method ,

with F. Rendl, Mathematical Programming B, 109(2/3):505-524, 2007.

• Computational Experience with a Bundle Approach for Semidefinite Cutting Plane Relaxations of Max-Cut and Equipartition,

with I. Fischer, G. Gruber and F. Rendl. Mathematical Programming B, 105(2/3):451-469, 2006.

• Recent Approaches to the Quadratic Assignment Problem,

with J. Povh, in: SOR'05 Proceedings of the 8 th International Symposium on Operational Research in Slovenia,

Nova Gorica, Slovenia, September 28-30, 2005.

• A Near Maximum Likelihood Decoding Algorithm for MIMO Systems Based on Graph Partitioning,

with A. Mobasher, M. Taherzadeh, A.K. Khandani, in Proceedings of IEEE International Symposium on Information Theory

(ISIT), Adelaide Convention Centre, Adelaide, Australia, September 4-9, 2005.

• A Randomization Method for Quasi-Maximum Likelihood Decoding,

with A. Mobasher, M. Taherzadeh, A.K. Khandani, in Proceedings of Canadian Workshop on Information Theory

(CWIT 2005), Montreal, Quebec, Canada, June 5-8, pp. 135-138, 2005.

• An Efficient Quasi-Maximum Likelihood Decoding for Finite Constellations,

with A. Mobasher, M. Taherzadeh, and A.K. Khandani, in Proceedings of the 39th Conference on Information Sciences

and Systems (CISS 2005), Johns Hopkins University, Baltimore, USA, March 16-18, 2005.

• On Self-Regular IPMs,

with M. Salahi and T. Terlaky (invited article). TOP, 12(2):209-300, 2004.

•  Bundle Methods in Combinatorial Optimization,

Department of Mathematics, University of Klagenfurt, Austria, PhD Thesis, July 4, 2003.

• Bounds for the Quadratic Assignment Problem Using the Bundle Method,

with F. Rendl, Discrete Optimization: Methods and Applications,

editors: U. Derigs, H.W. Hamacher, and U. Zimmermann, Braunschweig-Kaiserslautern-Köln, 287-305, 2003.

• The Bundle Method Applied to QAP,

with F. Rendl, in: SOR'01 Proceedings of the 6 th International Symposium on Operational Research in Slovenia,

Preddvor, Slovenia, September 26-28, 2001, 95-101.

• Mathematical Models of Hemodialysis,

with M. Jakic, M. Pavlekovic, in: 7 th International Conference on Operational Research,

Rovinj, Croatia, September 30 - October 2, 1998, 208-218.

• Application of the Triangle Congruence,

Journal of Croatian Mathematical Society 16:21-24, 1997.

• Opseg i povrsina snjezne pahuljice,

with V. Taslidzic, Journal of Mathematics and Physics (croat. Matematicko fizicki list), 43:76-80, 1998-99,

and in:

Mathematics and School (croat. Matematika i škola) 18/IV, editor: Element, Zagreb, Croatia, 74-76, 2002.

• Dynamic Model with an Equivalent Mass for the Analysis of Dynamic Characteristics Structures,

with D. Sotirov, in: Proceedings of 6 th Symposium on the Theoretical and Applied Mechanics, Struga,

Republic of Macedonia, October 1-3, 1998, 403-409.

Codes to download: