TY - GEN A1 - Lindner, Niels A1 - Reisch, Julian T1 - Parameterized Complexity of Periodic Timetabling N2 - Public transportation networks are typically operated with a periodic timetable. The Periodic Event Scheduling Problem (PESP) is the standard mathematical modelling tool for periodic timetabling. Since PESP can be solved in linear time on trees, it is a natural question to ask whether there are polynomial-time algorithms for input networks of bounded treewidth. We show that deciding the feasibility of a PESP instance is NP-hard even when the treewidth is 2, the branchwidth is 2, or the carvingwidth is 3. Analogous results hold for the optimization of reduced PESP instances, where the feasibility problem is trivial. To complete the picture, we present two pseudo-polynomial-time dynamic programming algorithms solving PESP on input networks with bounded tree- or branchwidth. We further analyze the parameterized complexity of PESP with bounded cyclomatic number, diameter, or vertex cover number. For event-activity networks with a special -- but standard -- structure, we give explicit and sharp bounds on the branchwidth in terms of the maximum degree and the carvingwidth of an underlying line network. Finally, we investigate several parameters on the smallest instance of the benchmarking library PESPlib. T3 - ZIB-Report - 20-15 KW - Parameterized complexity KW - Periodic timetabling KW - Treewidth KW - Branchwidth KW - Carvingwidth KW - Periodic Event Scheduling Problem Y1 - 2020 UR - https://opus4.kobv.de/opus4-zib/frontdoor/index/index/docId/7831 UR - https://nbn-resolving.org/urn:nbn:de:0297-zib-78314 SN - 1438-0064 ER -