Timetabling

Timetabling is the process of assigning activities to time slots and resources in a way that satisfies a set of constraints. It is used in schools and universities to create class schedules and exam calendars, but also appears in transportation, conferences, and other contexts where limited resources must be shared efficiently.

Key concepts include decision variables (which activity occurs when and on which resource), domains (possible times and rooms), and constraints. Hard constraints are non-negotiable, such as a teacher’s unavailability, room capacity, or a clash avoidance for students. Soft constraints express preferences and policies and are aimed at minimizing violations, such as avoiding early-morning slots for certain classes or balancing load.

Approaches range from manual planning to algorithmic methods. Many timetabling problems are modeled as constraint satisfaction problems (CSP) or as optimization problems solvable by integer programming or metaheuristics. Techniques include greedy construction, local search, graph coloring, and evolutionary algorithms. The objective is to satisfy hard constraints while optimizing soft constraints, often yielding one timetable or a set of good options.

A typical workflow starts with data collection (availability, room inventory, course requirements, enrolment). The problem is formulated, a solving method is chosen, and a timetable is produced and validated. Then dissemination and adjustments follow as changes arise.

Common challenges include scale, changing constraints, fairness among stakeholders, and robustness to late alterations. Effective timetabling improves resource utilization and reduces timetable clashes, supporting smoother operations and better satisfaction for staff and students.