Leader of the group Networks and Optimization: Daniel Dadush.

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)




No vacancies currently.


CWI and ProRail predict railway incidents

CWI and ProRail predict railway incidents

Centrum Wiskunde & Informatica and ProRail recently started a research collaboration in the area of the handling of incidents at the Dutch railways. It concerns a public private partnership between CWI and ProRail striking up a four year period. The research is aimed at prevention and handling of a broad spectrum of railway incidents, like disturbance of the railway infrastructure, people walking on the tracks and collisions.

CWI and ProRail predict railway incidents - Read More…

Current events

Dutch Seminar on Optimization (online series) with Jasper van Doornmalen (TU/e) and Daniel Brosch (Tilburg University)

  • 2022-05-24T16:00:00+02:00
  • 2022-05-24T17:00:00+02:00
May 24 Tuesday

Start: 2022-05-24 16:00:00+02:00 End: 2022-05-24 17:00:00+02:00

Online seminar

The Dutch Seminar on Optimization is an initiative to bring together researchers from the Netherlands and beyond, with topics that are centered around Optimization in a broad sense. We would like to invite all researchers, especially also PhD students, who are working on related topics to join the events. We hereby announce the following two talks, given by PhD-students:

Speaker: Jasper van Doornmalen (TU/e)
Title: Symmetry handling in binary programs through propagation
Date: Tuesday 24th May, 4:00pm CET

Symmetries of binary programs are known to dramatically slow down branch-and-bound procedures. A classical approach to handle permutation symmetries is to enforce that only one representative of equivalent (symmetric) solutions can be computed. In classical integer programming literature, among others, this is established by introducing symmetry handling constraints. This way, solutions that are not lexicographically maximal among the permuted solutions are cut off.

We present a propagation-based symmetry handling technique. Given a set of fixed variables (e.g., due to branching decisions), this technique identifies further variables that can be fixed to ensure that only lexicographically maximal solutions are computed. We present efficient algorithms to find such additional symmetry-based variable fixings for arbitrary sets of permutations and cyclic groups. In particular, for cyclic groups, we show that all possible fixings can be found in polynomial time even if the cyclic group has exponential order.

Our methods are implemented as a plugin in the academic integer programming solver SCIP, and we discuss the effectiveness of these methods on various symmetrical instances.

Speaker: Daniel Brosch (Tilburg University)
Title: The Symmetries of Flag-Algebras
Date: Tuesday 24th May, 4:30pm CET

Flag-Algebras, first introduced by Razborov in 2007, remain one of the most powerful tools in extremal combinatorics.  Recently a connection to polynomial optimization was discovered: We can recover Flag-Sums-of-Squares hierarchies by partially exploiting the symmetries of a polynomial optimization hierarchy. We continue from there and fully exploit the symmetries in this polynomial setting for two different hierarchies, one focusing on a low number of edges, and another focusing on a low number of vertices of appearing Flags. For the first, due to the high initial dimension of the hierarchy, a novel algorithm was needed to decompose modules of the symmetric group into irreducible submodules. We apply the reduced hierarchies to obtain outer approximations of graph-profiles, which model various open problems from extremal combinatorics.

N&O seminar: Stefan Schmid (TU Berlin)

  • 2022-06-15T11:00:00+02:00
  • 2022-06-15T12:00:00+02:00
June 15 Wednesday

Start: 2022-06-15 11:00:00+02:00 End: 2022-06-15 12:00:00+02:00

L0.17 and online

Everyone is welcome to attend the next N&O seminar with Stefan Schmid with the title 'Self-Adjusting Networks'.

The talk will take place in L017 at CWI, along with zoom support for remote participants. For more information and registration to get the Zoom link via e-mail, please contact Willem Feijen (willem.feijen at, Samarth Tiwari (samarth.tiwari at or Sven Polak (sven.polak at

Abstract: This talk will present the vision of self-adjusting networks: communication networks whose physical topology adapts to the traffic pattern it serves, in a demand-aware manner. Such networks are enabled by emerging reconfigurable optical technologies. It will be shown that the benefit of self-adjusting networks depends on the amount of “structure” there is in the demand, and an information-theoretical approach to measure the complexity of traffic traces will be presented to derive entropy-based metrics accordingly. Optimal offline and online algorithms to design self-adjusting networks whose performance matches the derived metrics asymptotically will be discussed.

Dutch Seminar on Optimization (online series) with Vera Traub (ETH Zürich)

  • 2022-06-30T16:00:00+02:00
  • 2022-06-30T17:00:00+02:00
June 30 Thursday

Start: 2022-06-30 16:00:00+02:00 End: 2022-06-30 17:00:00+02:00

Online seminar

Speaker: Vera Traub (ETH Zürich)


Better-Than-2 Approximations for Weighted Tree Augmentation and Forest Augmentation

Zoom link:
(Meeting ID: 849 0964 5595, Passcode: 772448)


The Weighted Tree Augmentation Problem (WTAP) is one of the most basic connectivity augmentation problems. It asks how to increase the edge-connectivity of a given graph from 1 to 2 in the cheapest possible way by adding some additional edges from a given set. In the first part of this talk we present the first algorithm that improves on the longstanding approximation ratio of 2 for WTAP.
In the second part of the talk we show how this algorithm can be used to obtain the first better-than-2 approximation algorithm for the Forest Augmentation Problem. In this problem we want to choose a minimum number of edges, among a given set of options, that we can add to a graph G to make it 2-edge connected. In contrast to the Tree Augmentation Problem, we do not require the given graph G to be connected.
This talk is based on joint works with Fabrizio Grandoni, Afrouz Jabal Ameli, and Rico Zenklusen.

Workshop on Semidefinite and Polynomial Optimization (Semester Programme)

  • 2022-08-29T00:00:00+02:00
  • 2022-10-02T23:59:59+02:00
August 29 Monday

Start: 2022-08-29 00:00:00+02:00 End: 2022-10-02 23:59:59+02:00


This workshop is dedicated to recent developments in semidefinite and polynomial optimization, and their applications in combinatorial and continuous optimization, discrete geometry and quantum information. The program (under construction) will consist of invited lectures by experts in the field. It will also feature lectures by younger researchers and ample time will be left for free discussions.

This workshop is co-orgnized by Jop Briët and Monique Laurent.

Here you can find more information on the program of CWI's Semidefinite and Polynomial Optimization Workshop.

Workshop on Solving Polynomial Equations and Applications (Semester Programme)

  • 2022-10-05T00:00:00+02:00
  • 2022-10-07T23:59:59+02:00
October 5 Wednesday

Start: 2022-10-05 00:00:00+02:00 End: 2022-10-07 23:59:59+02:00


Polynomial equations are at the heart of many problems in pure and applied mathematics. They form a powerful tool for modelling nonlinear phenomena in the sciences. Application areas range from robotics, chemistry and computer vision to quantum physics and statistics. Recent progress has made it possible to reliably solve challenging polynomial equations arising in such practical contexts. This workshop will feature a friendly introduction to existing methods, presentations of the latest software tools and research talks by experts in the field. The focus will be on new trends and methodology, as well as applications in the sciences.

This workshop is co-organized by Monique Laurent and Simon Telen.

Here you can find more information on the program of CWI's Solving Polynomial Equations and Applications workshop.

Workshop on Polynomial Optimization and Applications in Control and Energy (Semester Programme)

  • 2022-11-16T00:00:00+01:00
  • 2022-11-18T23:59:59+01:00
November 16 Wednesday

Start: 2022-11-16 00:00:00+01:00 End: 2022-11-18 23:59:59+01:00


This workshop is devoted to the application of polynomial optimization methods in the analysis and control of dynamical systems and energy networks. The polynomial optimization approach offers a powerful framework to model hard nonconvex, nonlinear control problems as infinite dimensional linear optimization problems over measure spaces. The rich interplay between functional analysis and operator theory, and real algebraic geometry, underlies the nowadays well-known moment/sum-of-squares hierarchy of relaxations, that allows to efficiently obtain converging sequences of bounds. This approach has also been recently developed to attack large optimal power flow problems in large electrical networks. The program (under construction) will feature lectures by experts in the field and ample time will be left for discussions.

This workshop is co-organized by Monique Laurent and Bert Zwart.

Here you can find more information on the program of CWI's Polynomial Optimization and Applications in Control and Energy workshop.


Associated Members


Current projects with external funding

  • Smart Heuristic Problem Optimization ()
  • Mixed-Integer Non-Linear Optimisation Applications (MINOA)
  • New frontiers in numerical nonlinear algebra (None)
  • Optimization for and with Machine Learning (OPTIMAL)
  • Polynomial Optimization, Efficiency through Moments and Algebra (POEMA)
  • Towards a Quantitative Theory of Integer Programming (QIP)

Related partners

  • Alma Mater Studiorum-Universita di Bologna
  • Alpen-Adria-Universität Klagenfurt
  • CNR Pisa
  • CNRS
  • Dassault Systèmes B.V.
  • IBM
  • Rheinische Friedrich-Wilhelmus Universitaet Bonn
  • Technische Universität Dortmund
  • Tilburg University
  • Tromsø, Norway
  • Universita degli Studi di Firenze
  • Universität Konstanz
  • University of Birmingham
  • Universiteit van Tilburg