A domain transformation approach for addressing staff scheduling problems

Staff scheduling is a complex combinatorial optimisation problem concerning allocation of staff to duty rosters in a wide range of industries and settings. This thesis presents a novel approach to solving staff scheduling problems, and in particular nurse scheduling, by simplifying the problem space through information granulation. The complexity of the problem is due to a large solution space and the many constraints that need to be satisfied. Published research indicates that methods based on random searches of the solution space did not produce good-quality results consistently. In this study, we have avoided random searching and proposed a systematic hierarchical method of granulation of the problem domain through pre-processing of constraints. The approach is general and can be applied to a wide range of staff scheduling problems. The novel approach proposed here involves a simplification of the original problem by a judicious grouping of shift types and a grouping of individual shifts into weekly sequences. The schedule construction is done systematically, while assuring its feasibility and minimising the cost of the solution in the reduced problem space of weekly sequences. Subsequently, the schedules from the reduced problem space are translated into the original problem space by taking into account the constraints that could not be represented in the reduced space. This two-stage approach to solving the scheduling problem is referred to here as a domaintransformation approach. The thesis reports computational results on both standard benchmark problems and a specific scheduling problem from Kajang Hospital in Malaysia. The results confirm that the proposed method delivers highquality results consistently and is computationally efficient. ADDRESSING STAFF SCHEDULING PROBLEMS iv Publications/Disseminations During PhD Period Delivered Workshop Presentation Granular Approach to Personnel Scheduling: Inspiration from the Hirota Lab. In 2009 International Workshop on Advanced Computational Intelligence and Intelligent Informatics (IWACIII2009), November 7th, Tokyo Institute of Technology, Tokyo, Japan. (EXCELLENT PRESENTATION AWARD: Appendix H) Delivered Keynote Lecture: Domain transformation in nurse scheduling. In 2014 International Conference on Artificial Intelligence, Energy and Manufacturing Engineering (IIE ICAEME2015), Dubai, UAE, 7–8 January 2015 (Appendix J) Participated in Competition: Baskaran, G. (2015). Domain transformation in nurse scheduling problem using integer programming. In 2015 National Innovation and Invention Competition through Exhibition (iCompEx’15), Politeknik Sultan Abdul Halim Mu’adzam Shah, Kedah, 24–26 March. (GOLD MEDAL: Appendix K). Baskaran, G. (2013). Information granulation to the nurse scheduling problem. In 3MT: Three Minute Thesis. University of Nottingham, Malaysia, 3 November. Fully Refereed Papers Published: Baskaran, G., Bargiela, A. & Qu, R. (2015). Domain transformation using greedy algorithm in nurse scheduling. In 2015 International Conference on Artificial Intelligence, Energy and Manufacturing Engineering (IIE ICAEME2015). Dubai, UAE, 7–8 Jan, pp. 92–98, Paper ID: E0115039, ISBN: 978–93–84422–05–9. Doi: http://dx.doi.org/10.15242/IIE. E0115039 ADDRESSING STAFF SCHEDULING PROBLEMS v Baskaran, G., Bargiela, A. & Qu, R. (2014). Integer programming: Using branch-and-bound to solve the nurse scheduling problem. In 2014 International Conference on Artificial Intelligence and Manufacturing Engineering (IIE ICAIME2014). Dubai, UAE, 25–26 Dec, pp. 211–217, Paper ID: U1214025, ISBN 978–93–84468–11–8. Baskaran, G., Bargiela, A. & Qu, R. (2014). Seeing the bigger picture: Domain transformation approach to the nurse scheduling problem. Australian Journal of Basic and Applied Sciences (AENSI Journal), 8(24) Special: 308–320, ISSN:1991–8178. In: International Conference on Science, Engineering and Technology, Jakarta, Indonesia. (BEST PAPER AWARD: Appendix I). Baskaran, G., Bargiela, A. & Qu, R. (2014). New solution for a benchmark nurse scheduling problem using integer programming. In International Conference on Information, Management Science and Application (ICIMSA 2014). Beijing, China, pp. 350–353, ISBN (IEEE Xplore): 978–1-4799–6541–0/14/$31.00 Baskaran, G., Bargiela, A. & Qu, R. (2014). Simulation of scheduling and cost effectiveness of nurses using domain transformation method. In 28th European Conference for Modelling and Simulation (ECMS 2014). Brescia, Italy, pp. 226–234, doi:10.7148/2014–0226 Baskaran, G., Bargiela A. & Qu, R. (2013). A study of cost effective scheduling of nurses based on the domain transformation method. In 27th European Conference on Modelling and Simulation (ECMS 2013). Alesund, Norway, doi:10.7148/2013–0309 Baskaran, G., Bargiela, A. & Qu, R. (2009). Hierarchical method for nurse rostering based on granular pre-processing of constraints. In Proceedings of 23rd European Conference on Modelling and Simulation. Madrid, Spain, doi:10.7148/2009–0855–0860