A simulated annealing approach to the curriculum-based course timetabling problem

Course timetabling is a typical problem that all universities around the world have to face every semester. There exist a number of variants of this problem, depending on the specific requirements of the institution involved [13]. Thanks also to the international timetabling competition ITC-2007 [11], two formulations have, to some extent, lifted up to the status of “standard”. These are the so-called Post-Enrolment Course Timetabling (PE-CTT) [8] and CurriculumBased Course Timetabling (CB-CTT) [6]. The distinguishing difference between the two is the origin of the conflict matrix between courses, which is based on student enrolments and on predefined curricula, respectively. This is however only one of the differences, which actually include also many other features and cost components. Indeed, in the PE-CTT each event is self-standing, whereas in the CB-CTT a curriculum is composed by different courses that consist of multiple lectures and share the same students. In addition, the soft constraints are diverse: in the PE-CTT they are all related to events, penalising late, consecutive and isolated ones; in the CB-CTT they mainly involve curricula and courses, penalising isolated lectures in a curriculum, trying to minimise the number of days in which lectures of the same course are spread and the room transfers. In this work we focus on CB-CTT, building upon our previous work on this problem [3]. Some of the ideas, however, are transferred from work on PE-CTT [5], on which we have obtained good results, including many new best-known solutions, applying a similar approach.