Retimetabling

Retimetabling is the process of updating an existing timetable in response to new constraints, disruptions, or changing requirements. It is commonly used in educational settings to adjust class schedules and room assignments, but the concept also applies to conference planning, exam timetabling, and other contexts where time slots and resources must be allocated without overlap.

The primary goal of retimetabling is to restore or improve feasibility while minimizing disruption. Typical triggers include changes in room availability, instructor or student enrollment, course offerings, or policy requirements. Practical objectives often include avoiding conflicts for students and staff, respecting hard constraints (such as room capacities and time-slot availability), and minimizing the number of changed events or the impact on preferences and workloads.

Retimetabling is usually approached as a computational problem. Methods include constraint satisfaction, integer programming, SAT/Boolean formulations, and various metaheuristics such as local search, genetic algorithms, and simulated annealing. Solutions are evaluated using objective functions that may combine hard constraint satisfaction with penalties for undesirable outcomes, such as moved classes, ungapped schedules, or poor distribution of workload.

The typical process involves data collection, constraint modeling, solver execution, solution analysis, and stakeholder communication. Depending on the scale, retimetabling can be done iteratively to accommodate incremental changes, or as a one-off redesign. Challenges include the combinatorial complexity of schedules, propagation of changes, and ensuring solutions remain interpretable and acceptable to users.