University course timetabling using constraint handling rules

Timetabling the courses offered at the Computer Science Department of the U niversity of Munich requires the processing of hard and soft constraints. H ard constraints are conditions that must be satisfied soft constraints, how ever, may be violated, but should be satisfied as much as possible. This pa per shows how to model the timetabling problem as a partial constraint sati sfaction problem and gives a concise finite domain solver implemented with constraint handling rules that, by performing soft constraint propagation, allows for making soft constraints an active part of the problem-solving pr ocess. Furthermore, efficiency is improved by reusing parts of the timetabl e of the previous year. This prototype needs only a few minutes to create a timetable while manual timetabling usually takes a few days. This was pres ented at the Systems'98 Computer Fair in Munich and several universities ha ve inquired about it.