Networks such as traffic, communications and energy networks form the backbone of our society. These networks are increasingly complex.
“As a result of this increasing complexity, there is a greater chance over time that something will go wrong or that a network will become unstable,” explains Mandjes. “As scientists, but also as a whole society, we must have the courage to think creatively to ensure that these networks, which are increasingly subject to intensive use, will continue to be used efficiently in the future, without stop being reliable. That’s why the research we’re carrying out within NETWORKS is so important.’
Different researchers, different ideas
NETWORKS is a 10-year research programme, funded by a €22.7 million Gravitation grant from the Netherlands Organization for Scientific Research (NWO). In addition to the UvA, Eindhoven University of Technology (TU/e), Leiden University (UL) and the Center for Mathematics and Computer Science (CWI) are participating.
Mandjes: “We wrote the research proposal with the common thread that we wanted to tackle this topic together and that helped us move forward with this project. And these are not just empty words; all parties are really willing to learn about other disciplines. For example, we’re increasing the interaction between the principal investigators, which sometimes works well, to be honest, but it’s often a challenge because all the senior investigators have their own agenda.
Scientists with their own agenda? What’s new, you might say? As a project leader, this means you have to be flexible. Mandjes has managed to find his own way here: ‘I try to be an invisible leader; my goal is to listen to what people want themselves, certainly without forcing them to go in a certain direction. Within these margins, it still seems possible to do all kinds of things to achieve great synergy.’
A wide field of research
This approach seems to work well. Research within the broad NETWORKS program focuses on the stochastic (the outcome depends on chance or coincidence) and algorithmic (the instructions are used to achieve a goal) aspects of networks. The focus is on the modeling, understanding, control and optimization of complex and highly volatile networks. The program consists of two branches: ‘Network Structure’, which is more about describing networks, and ‘Network Configuration’, which is more about designing networks.
An example of deep and challenging research takes place in “network structure” when scientists look at the boundaries of graphs. A graph is a schematic network of points, nodes, paths, etc. You can allow this network to grow, subject to certain regularity requirements, after which you can investigate the limits of the graph. In recent work, Mandjes has been examining the stochastic behavior of graph boundaries, building on the work of the likes of Abel Prize-winning mathematician SRS Varadhan and the unofficial Nobel Prize in Mathematics.
Understand each other
While this is the core aspect of the program, NETWORKS scientists have increasingly begun to look at specific applications. “We seek to connect with fields such as social sciences and economics, to ensure that our knowledge is well received,” says Mandjes. “This type of collaboration is not obvious because each field of study has its own language. First you look at a specific topic from your own experience, then you have to talk a lot and adapt your models to achieve a result that is relevant in practice.’
For example, one of the studies dealt with the dynamics of opinion formation, in order to understand phenomena such as polarization. The researchers worked on models that can explain a wider spectrum of opinion dynamics. NETWORKS also carried out a project with civil engineers, which recently resulted in a publication in a renowned transport academic journal.
Mandjes: ‘The research dealt with routing in a network in which accidents can occur. This model goes back to Dijkstra in a way, but our model allows for all kinds of additional effects to be taken into account: daily patterns and less predictable events like accidents. We will talk to TomTom about this soon.
Development in progress
Back to Edsger Dijkstra. One of his most famous statements is: ‘It is not the task of the University to offer what society demands, but to give what society needs’. A university must respond to what will be necessary in our society in the future. This is the only way to stay ahead as a “net country”. To do this, you must constantly develop as a researcher.
Mandjes confirms this: “The challenge is to keep up with developments. For example, take the large amounts of data that have become available in recent years. How can you use this data when managing networks? To find out, I will have to learn about areas that are new to me, such as machine learning and other data-driven techniques.There are great opportunities here.
Annual review Faculty of Sciences 2021
This interview was also published in the annual review of the Faculty of Science of the University of Amsterdam. Read our annual review of news and background on teaching and research in the Faculty of Science in 2021, including interviews with faculty, researchers and students, enrollment facts and figures, and staff news about organizational developments and our valorization activities.