10188 2025 eng 397 402 conferenceobject 0 -- -- -- The Periodic Event Scheduling Problem (PESP) is a notoriously hard combinatorial optimization problem, essential for the design of periodic timetables in public transportation. The coefficients of the integer variables in the standard mixed integer linear programming formulations of PESP are the period time, e.g., 60 for a horizon of one hour with a resolution of one minute. In many application scenarios, lines with different frequencies have to be scheduled, leading to period times with many divisors. It then seems natural to consider derived instances, where the period time is a divisor of the original one, thereby smaller, and bounds are scaled and rounded accordingly. To this end, we identify two rounding schemes: wide and tight. We then discuss the approximation performance of both strategies, in theory and practice. Operations Research Proceedings 2023 10.1007/978-3-031-58405-3_51 Lecture Notes in Operations Research yes publish urn:nbn:de:0297-zib-92315 2023-11-02 Enrico Bortoletto Niels Lindner Guido Voigt Niels Lindner Malte Fliedner Knut Haase Wolfgang Brüggemann Kai Hoberg Jörn Meissner Mathematical Optimization MODAL-Gesamt Lindner, Niels Bortoletto, Enrico Network Optimization MODAL-MobilityLab Mathplus-PaA3 Applied Optimization