Description
Leader of the group Networks and Optimization: Guido Schäfer.
In today’s society, complex systems surround us. From transport and traffic, to behavioral economics and operations management, real-world applications often demand that we identify simple, optimal solutions among a huge set of possibilities. Our research group Networks and Optimization (N&O) does fundamental research to tackle such challenging optimization problems.
We develop algorithmic methods to solve complex optimization problems efficiently. Our research provides efficient algorithms to some of the most challenging problems, for example, in planning, scheduling and routing. To come up with the best optimization algorithms, we combine and extend techniques from different disciplines in mathematics and computer science.
N&O covers a broad spectrum of optimization aspects. Our expertise ranges from discrete to continuous optimization and applies to centralized and decentralized settings. We focus on both problem-specific methods and universal toolkits to solve different types of optimization problems. The key in our investigations is to understand and exploit combinatorial structures, such as graphs, networks, lattices and matroids. Our research is of high scientific impact and contributes to various fields.
In several cooperations with industry partners, the algorithmic techniques that we develop in our group have proven useful to solve complex real-world problems. We are always interested in new algorithmic challenges arising in real-world applications and are open to new cooperations.
Watch our group video to get a glimpse of our activities.
Video about our collaboration with ProRail (in Dutch)
Vacancies
PhD students / Early Stage Researchers on the subject of Polynomial Optimization, Efficiency through Moments and Algebra.
Centrum Wiskunde & Informatica (CWI) has vacancies in the Networks and Optimization research group for two talented PhD students / Early Stage Researchers on the subject of Polynomial Optimization, Efficiency through Moments and Algebra. The vacancies are within the research consortium POEMA (Polynomial Optimization, Efficiency through Moments and Algebra).
News
Jie Li and Sophie Huiberts selected to participate in the 7th Heidelberg Laureate Forum
Jie Li from the DIS group and Sophie Huiberts from the N&O group have been selected to participate in the 7th Heidelberg Laureate Forum (HLF). The annual HLF event selects a small group of 200 most qualified Young Researchers worldwide to meet pre-eminent scientists from the fields of mathematics and computer science.
Monique Laurent member of Royal Holland Society of Sciences and Humanities
Researcher and MT member Monique Laurent (CWI and UvT) has been invited to become a member of the Royal Holland Society of Sciences and Humanities (Koninklijke Hollandsche Maatschappij der Wetenschappen – KHMW) in Haarlem, the oldest academic society in the Netherlands.
CWI and Dassault Systèmes start PPS project to improve supply chain technology
CWI and Dassault Systèmes recently started a collaboration in the field of optimization technology for businesses.
Marie Curie ITN grant awarded to POEMA network
Recently, the EU awarded a Marie Skłodowska-Curie Innovative Training Networks (ITN) grant for POEMA – ‘Polynomial Optimization, Efficiency through Moments and Algebra’. The consortium consists of 14 academic and industrial partners, such as CWI, Tilburg University, Inria and IBM.
Current events
N&O seminar: Sahil Singla (Princeton University and Institute for Advanced Study)
- 2019-08-27T11:00:00+02:00
- 2019-08-27T12:00:00+02:00
N&O seminar: Sahil Singla (Princeton University and Institute for Advanced Study)
Start: 2019-08-27 11:00:00+02:00 End: 2019-08-27 12:00:00+02:00
Everyone is welcome to attend the N&O lecturen of Sahil Singla with the title 'Improved Truthful Mechanisms for Combinatorial Auctions with Submodular Bidders'.
Abstract: A longstanding open problem in Algorithmic Mechanism Design is to design computationally efficient truthful mechanisms for (approximately) maximizing welfare in combinatorial auctions with submodular bidders. The first such mechanism was obtained by Dobzinski, Nisan, and Schapira [STOC’06] who gave an O(log^2 m)-approximation where m is number of items. This problem has been studied extensively since, culminating in an O(\sqrt{log m})-approximation mechanism by Dobzinski [STOC’16]. We present a computationally-efficient truthful mechanism with approximation ratio that improves upon the state-of-the-art by an exponential factor. In particular, our mechanism achieves an O((loglog m)^3)-approximation in expectation, uses only O(n) demand queries, and has universal truthfulness guarantee. This settles an open question of Dobzinski on whether Θ(\sqrt{log m}) is the best approximation ratio in this setting in negative.
This is joint work with Sepehr Assadi and it will appear in FOCS 2019.
PhD defence Pieter Kleer (N&O)
- 2019-09-09T15:45:00+02:00
- 2019-09-09T17:15:00+02:00
PhD defence Pieter Kleer (N&O)
Start: 2019-09-09 15:45:00+02:00 End: 2019-09-09 17:15:00+02:00
Everyone is welcome to attend the public defence of Pieter Kleer, of his thesis 'When Nash met Markov: Novel results for pure Nash equilibria and the switch Markov chain'.
Promotors: Prof.dr. Guido Schäfer and Prof.dr. Lex Schrijver
CWI-Inria Workshop
- 2019-09-17T13:00:00+02:00
- 2019-09-18T16:00:00+02:00
CWI-Inria Workshop
Start: 2019-09-17 13:00:00+02:00 End: 2019-09-18 16:00:00+02:00
Everyone is welcome to attend the third annual workshop of the CWI-Inria International Lab. For registration, please visit the website. Also to see the full program.
PhD defence Sander Gribling (N&O)
- 2019-09-30T13:30:00+02:00
- 2019-09-30T15:00:00+02:00
PhD defence Sander Gribling (N&O)
Start: 2019-09-30 13:30:00+02:00 End: 2019-09-30 15:00:00+02:00
Everyone is welcome to attend the public defence of Sander Gribling of his thesis 'Applications of optimization to factorization ranks and quantum information theory'.
Promotors: Prof.dr. M. Laurent (CWI/Tilburg University) and Prof.dr. R.M. de Wolf (CWI/UvA)
- Email: Susanne van Dam
- Phone: 020-5924189
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iCal
Members
Associated Members
Publications
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Chen, J.-J, Bansal, N, Chakraborty, S, & von der Brüggen, G. (2018). Packing sporadic real-time tasks on identical multiprocessor systems. In 29th International Symposium on Algorithms and Computation (pp. 71:1–71:14). doi:10.4230/LIPIcs.ISAAC.2018.71
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Dadush, D.N, Nikolov, A, Talwar, K, & Tomczak-Jaegermann, N. (2018). Balancing vectors in any norm. In Proceedings - Annual IEEE Symposium on Foundations of Computer Science, FOCS (pp. 1–10). doi:10.1109/FOCS.2018.00010
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Carvalho Rodrigues, F, Schäfer, G, & Xavier, E.C. (2018). On the effectiveness of connection tolls in fair cost facility location games. In Proceedings of the 19th Italian Conference on Theoretical Computer Science (pp. 36–47).
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van Heuven van Staereling, I.I. (2018). Tree decomposition methods for the periodic event scheduling problem. In OpenAccess Series in Informatics. doi:10.4230/OASIcs.ATMOS.2018.6
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Carstens, C.J, & Kleer, P.S. (2018). Speeding up switch Markov chains for sampling bipartite graphs with given degree sequence. In Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques (APPROX/RANDOM 2018) (pp. 36:1–36:18). doi:10.4230/LIPIcs.APPROX-RANDOM.2018.36
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Amanatidis, G, Birmpas, G, & Markakis, V. (2018). Comparing approximate relaxations of envy-freeness. In IJCAI International Joint Conference on Artificial Intelligence (pp. 42–48).
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Bansal, N, Dadush, D.N, Garg, S, & Lovett, S. (2018). The Gram-Schmidt Walk: A Cure for the Banaszczyk Blues. In Proceedings of the 50th Annual ACM SIGACT Symposium on Theory of Computing, STOC 2018 (pp. 587–597). doi:10.1145/3188745.3188850
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Dadush, D.N, & Huiberts, S. (2018). A friendly smoothed analysis of the simplex method. In Proceedings of the Annual ACM Symposium on Theory of Computing (pp. 214–227). doi:10.1145/3188745.3188826
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Kamphorst, B. (2018, May 31). Heavy-traffic behaviour of scheduling policies in queues.
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Amanatidis, G, Green, B, & Mihail, M. (2018). Connected realizations of joint-degree matrices. Discrete Applied Mathematics. doi:10.1016/j.dam.2018.04.010
Current projects with external funding
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Continuous Methods in Discrete Optimization ()
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Wiskundecluster DIAMANT ()
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Smart Heuristic Problem Optimization
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Approximation Algorithms, Quantum Information and Semidefinite Optimization (AQSO)
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Mixed-Integer Non-Linear Optimisation Applications (MINOA)
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Polynomial Optimization, Efficiency through Moments and Algebra (POEMA)
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Vóórkomen en voorkómen van incidenten op het spoor (PPS Prorail)
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Towards a Quantitative Theory of Integer Programming (QIP)
Related partners
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Alma Mater Studiorum-Universita di Bologna
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Alpen-Adria-Universität Klagenfurt
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CNR Pisa
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CNRS
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Dassault Systèmes B.V.
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IBM
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INRIA
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Prorail
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Rheinische Friedrich-Wilhelmus Universitaet Bonn
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Technische Universität Dortmund
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Tilburg University
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Tromsø, Norway
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Universita degli Studi di Firenze
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Universität Konstanz
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University of Birmingham