TOP (2015) 23:313–349 DOI 10.1007/s11750-015-0366-z INVITED PAPER An overview of curriculum-based course timetabling Andrea Bettinelli · Valentina Cacchiani · Roberto Roberti · Paolo Toth Published online: 19 March 2015 © Sociedad de Estadística e Investigación Operativa 2015 Abstract In 2007, the Second International Timetabling Competition (ITC-2007) has been organized and a formal definition of the Curriculum-Based Course Timetabling (CB-CTT) problem has been given, by taking into account several real-world con- straints and objectives while keeping the problem general. CB-CTT consists of finding the best weekly assignment of university course lectures to rooms and time periods. A feasible schedule must satisfy a set of hard constraints and must also take into account a set of soft constraints, whose violation produces penalty terms to be minimized in the objective function. From ITC-2007, many researchers have developed advanced models and methods to solve CB-CTT. This survey is devoted to review the main works on the topic, with focus on mathematical models, lower bounds, and exact and heuristic algorithms. Besides giving an overview of these approaches, we highlight interesting extensions that could make the study of CB-CTT even more challenging and closer to reality. This invited paper is discussed in the comments available at doi:10.1007/s11750-015-0362-3, doi:10.1007/s11750-015-0363-2, doi:10.1007/s11750-015-0364-1, doi:10.1007/s11750-015-0365-0. A. Bettinelli · V. Cacchiani · P. Toth (B ) DEI, University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy e-mail: paolo.toth@unibo.it A. Bettinelli e-mail: andrea.bettinelli@unibo.it V. Cacchiani e-mail: valentina.cacchiani@unibo.it R. Roberti Department of Transport, Technical University of Denmark, 2800 Kgs Lyngby, Denmark e-mail: rorob@transport.dtu.dk 123