• Publications
• Influence
Multi-criteria Shortest Paths in Time-Dependent Train Networks
• Mathematics, Computer Science
• WEA
• 30 May 2008
A new prototype to solve the problem of finding all Pareto-optimal solutions in a multi-criteria setting of the shortest path problem in time-dependent graphs based on a multi -criteria generalization of Dijkstra's algorithm is presented. Expand
Scheduling Bidirectional Traffic on a Path
• Mathematics, Computer Science
• ICALP
• 27 April 2015
This work studies the fundamental problem of scheduling bidirectional traffic along a path composed of multiple segments and gives polynomial algorithms for the setting with restricted compatibilities between jobs on a single and any constant number of segments, respectively. Expand
The Complexity of Computing a Robust Flow
• Computer Science, Mathematics
• Oper. Res. Lett.
• 26 April 2017
A new hardness proof is presented, establishing that the problem is strongly NP-hard, even when only two different capacity values occur and the number of paths is polynomial in the size of the input. Expand
A polygon is determined by its angles
• Computer Science, Mathematics
• Comput. Geom.
• 1 October 2011
It is proved that the angle measurements at all vertices of a simple polygon together with the order of the vertices along the boundary uniquely determine the polygon (up to similarity). Expand
Scheduling Transfers of Resources over Time: Towards Car-Sharing with Flexible Drop-Offs
• Computer Science
• LATIN
• 11 April 2016
We consider an offline car-sharing assignment problem with flexible drop-offs, in which n users (customers) present their driving demands, and the system aims to assign the cars, initially located atExpand
Packing a Knapsack of Unknown Capacity
• Mathematics, Computer Science
• SIAM J. Discret. Math.
• 6 July 2017
It is shown that there is always a policy that packs a value within factor 2 of the optimum packing, irrespective of the actual capacity, and the problem of deciding whether a given universal policy achieves a factor of $\alpha$ is ${\mathsf{coNP}}$-complete. Expand
Improved Lower Bound for Competitive Graph Exploration
• Computer Science, Mathematics
• Theor. Comput. Sci.
• 25 February 2020
We give an improved lower bound of 10/3 on the competitive ratio for the exploration of an undirected, edge-weighted graph with a single agent that needs to return to the starting location afterExpand
Tight Bounds for Online TSP on the Line
This work considers the online traveling salesperson problem (TSP), where requests appear online over time on the real line and need to be visited by a server initially located at the origin, and gives an algorithm with running time O(n2) for closed offline TSP on the line with release dates and shows that both variants of offline D ial -A-R ide on the lines are NP-hard for any capacity c ≥ 2 of the server. Expand
Undirected Graph Exploration with ⊝(log log n) Pebbles
• Computer Science, Mathematics
• SODA
• 10 January 2016
This work considers the fundamental problem of exploring an undirected and initially unknown graph by an agent with little memory and shows that for an agent O(log log n) distinguishable pebbles and bits of memory are sufficient to explore any bounded-degree graph with at most n vertices. Expand
Fast Collaborative Graph Exploration
• Mathematics, Computer Science
• ICALP
• 8 July 2013
The first strategy which performs exploration of a graph with n vertices at a distance of at most D from r in time O(D), using a team of agents of polynomial size k=Dn1+e 0 is provided, without knowledge of global parameters such as n or D. Expand