Aktuelles
Dissertation Defense 7 Oct 2025
Christoph Grüne successfully defended his thesis entitled Computational Complexity of Problems in Robust, Bilevel and Online Optimization. Congratulations to Dr. Grüne!
Welcome 1 Oct 2025
Jakob Lindner joined our group as a PhD student. Welcome, Jakob!
Best Paper Award at SAGT 2025 3 Sep 2025
We are excited and thankful that our paper "Persuading Agents in Opinion Formation Games" was selected to receive the Best Paper Award at SAGT 2025.
New Paper at SAGT 2025 2 Jul 2025
Our paper "Persuading Agents in Opinion Formation Games" (by Martin Hoefer, Tim Koglin, Tolga Tel) was accepted at the 18th International Symposium on Algorithmic Game Theory (SAGT 2025).
Two Papers at MFCS 2025 27 Jun 2025
Two papers of our group were accepted at the 50th International Symposium on Mathematical Foundations of Computer Science (MFCS 2025).
- Online Knapsack Problems with Estimates
(by Jakub Balaban, Matthias Gehnen, Henri Lotze, Finn Seesemann, Moritz Stocker) - On the Complexity of Recoverable Robust Optimization in the Polynomial Hierarchy
(by Christoph Grüne, Lasse Wulf)
Dissertation Defense 15 May 2025
Marco Schmalhofer successfully defended his thesis entitled Algorithmic Aspects of Fair Division. Congratulations to Dr. Schmalhofer!
New Paper at EC 2025 14 May 2025
Our paper "Welfare and Beyond in Multi-Agent Contracts" (by Gil Aharoni, Martin Hoefer, Inbal Talgam-Cohen) was accepted at the 26th Conference on Economics and Computation (EC 2025), the international top conference at the intersection of economics and computer science.
New Paper at SAND 2025 28 Mar 2025
Our paper "Dynamic Debt Swapping in Financial Networks" (by Henri Froese, Martin Hoefer, Lisa Wilhelmi) was accepted at the 4th Symposium on Algorithmic Foundations of Dynamic Networks (SAND 2025).
New Paper in Operations Research, Data Analytics and Logistics 14 Mar 2025
In events of distress, an available naval rescue vessel from a home station with the lowest response time is dispatched. But how should rescue vessels be allocated to home stations when their operational availability changes over time due to low tides? In our paper "Rescue Vessel Allocation in Tidal Waters of the North and Baltic Sea" (by Tom Mucke, Alexander Renneke, Finn Seesemann, Felix Engelhardt) we build a mathematical model for this problem. We show that optimizing expected response times to distress calls is NP-hard. However, we provide an Integer Programming formulation and propose two methods of simplifying the model. We then compare the effectiveness of the models in a case study based on real-world data. Results show that the simplified models can be solved to de facto optimality, outperforming the results attained by the full model. The paper has been accepted for publication in Operations Research, Data Analytics and Logistics.
New Paper at AISTATS 2025 24 Jan 2025
Our paper "Independent Learning in Performative Markov Potential Games" (by Rilind Sahitaj, Paulius Sasnauskas, Yiğit Yalın, Debmalya Mandal, Goran Radanovic) was accepted at the 28th International Conference on Artificial Intelligence and Statistics (AISTATS 2025), an international top conference at the intersection of machine learning and statistics.
New Paper at IPCO 2025 22 Jan 2025
Our paper "Completeness in the Polynomial Hierarchy for many natural Problems in Bilevel and Robust Optimization" (by Christoph Grüne, Lasse Wulf) was accepted at the 26th Conference on Integer Programming and Combinatorial Optimization (IPCO 2025).
New Paper at AAMAS 2025 19 Dec 2024
Our paper "Opinion Dynamics with Median Aggregation" (by Petra Berenbrink, Martin Hoefer, Marten Maack, Malin Rau, Dominik Schallmoser, Lisa Wilhelmi) was accepted as full paper at the 24th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2025), the international top conference in multi-agent systems.
New Paper at STACS 2025 13 Dec 2024
Our paper "Designing Exploration Contracts" (by Martin Hoefer, Conrad Schecker, Kevin Schewior) was accepted at the 42nd International Symposium on Theoretical Aspects of Computer Science (STACS 2025), a leading conference in theoretical computer science.
Visitor 11 Dec 2024
Daniel Schmand is visiting our group Dec 11-13.
Welcome 1 Dec 2024
Sukanya Pandey joined our group as a postdoc. Welcome, Sukanya!
New Paper at SOFSEM 2025 12 Nov 2024
Treasure hunt problems are a variant of graph exploration problems, in which a ''searcher'' needs to find a hidden treasure that is located at a designated vertex in an unknown graph. In our paper ''The Complexity of Graph Exploration Games'' (by Janosch Fuchs, Christoph Grüne, Tom Janßen), we analyze the complexity of different variations of graph exploration and treasure hunt problems. These problems usually come as online problems. We assume that the searcher carries a map of an isomorphic copy of the graph for orientation. We show PSPACE-completeness for the problem of exploring the graph completely or finding the treasure. The paper has been accepted at the 50th International Conference of Current Trends in Theory and Practice of Computer Science (SOFSEM 2025).
New Paper in Mathematics of Operations Research 10 Nov 2024
The Nash social welfare, given by the product of agent valuations, is a popular objective when assigning indivisble goods to a set of agents. While it has desirable fairness properties, optimization is in general intractable. In our paper ''Maximizing Nash Social Welfare in 2-Value Instances: Delineating Tractability'' (by Hannaneh Akrami, Bhaskar Ray Chaudhury, Martin Hoefer, Kurt Mehlhorn, Marco Schmalhofer, Golnoosh Shahkarami, Giovanna Varricchio, Quentin Vermande, Ernest van Wijland) we examine the (in-)tractability in one of the most elementary scenarios, in which additive valuations are based on two non-negative integers p > q. Interestingly, if the ratio p/q (after reduction) is integral or half-integral, we obtain efficient algorithms to find an optimal solution. If p/q has denominator at least 3, the problem becomes intractable. The paper has been accepted for publication in Mathematics of Operations Research, a leading journal in operations research.
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