Abstract
Break scheduling problems arise in working areas where breaks are indispensable, e.g., in air traffic control, supervision, or assembly lines. We regard such a problem from the area of supervision personnel. The objective is to find a break assignment for an existing shiftplan such that various constraints reflecting legal demands or ergonomic criteria are satisfied and such that staffing requirement violations are minimised. We prove the NP-completeness of this problem when all possible break patterns for each shift are given explicitly as part of the input. To solve our problem we propose two variations of a memetic algorithm. We define genetic operators, a local search based on three neighbourhoods, and a penalty system that helps to avoid local optima. Parameters influencing the algorithms are experimentally evaluated and assessed with statistical methods. We compare our algorithms, each with the best parameter setting according to the evaluation, with the state-of-the-art algorithm on a set of 30 real-life and randomly generated instances that are publicly available. One of our algorithms returns improved results on 28 out of the 30 benchmark instances. To the best of our knowledge, our improved results for the real-life instances constitute new upper bounds for this problem
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References
Aykin T (1996) Optimal shift scheduling with multiple break windows. Manag Sci 42:591–603
Aykin T (2000) A comparative evaluation of modelling approaches to the labour shift scheduling problem. Eur J Oper Res 125:381–397
Bechtold S, Jacobs L (1990) Implicit modelling of flexible break assignments in optimal shift scheduling. Manag Sci 36(11):1339–1351
Beer A, Gaertner J, Musliu N, Schafhauser W, Slany W (2008) An iterated local search algorithm for a real-life break scheduling problem. In: Proceedings of Matheuristics 2008, 2nd international workshop on model based Metaheuristics, Bertinoro
Beerm A, Gaertner J, Musliu N, Schafhauser W, Slany W (2008) Scheduling breaks in shift plans for call centers. In: Proceedings of the 7th international conference on the practice and theory of automated timetabling, Montreal
Beer A, Gärtner J, Musliu N, Schafhauser W, Slany W (2010) An AI-based break-scheduling system for supervisory personnel. IEEE Intell Syst 25(2):60–73
Burke EK, Cowling PI, Causmaecker PD, Berghe GV (2001) A memetic approach to the nurse rostering problem. Appl Intell 15(3):199–214
Côté M-C, Gendron B, Quimper C-G, Rousseau L-M (2011) Formal languages for integer programming modeling of shift scheduling problems. Constraints 16(1):55–76
Côté M-C, Gendron B, Rousseau L-M (2011) Grammar-based integer programming models for multiactivity shift scheduling. Manag Sci 57(1):151–163
Cotta C, Fernández AJ (2007) Memetic algorithms in planning, scheduling, and timetabling. Evolutionary scheduling. Springer, Berlin
Dantzig GB (1954) A comment on Eddie’s traffic delays at toll booths. Oper Res 2:339–341
Dechter R, Meiri I, Pearl J (1991) Temporal constraint networks. Artif Intell 49:61–95
Di Gaspero L, Gärtner J, Kortsarz G, Musliu N, Schaerf A, Slany W (2007) The minimum shift design problem. Ann Oper Res 155:79–105
Garey M, Johnson D (1979) Computers and intractability: a guide to the theory of NP-completeness. W.H. Freeman, New York
Gärtner J, Musliu N, Slany W (2004) A heuristic based system for generation of shifts with breaks. In: Proceedings of the 24th SGAI international conference on innovative techniques and applications of artificial intelligence, Cambridge
Gaspero LD, Gärtner J, Musliu N, Schaerf A, Schafhauser W, Slany W (2010) A hybrid LS-CP solver for the shifts and breaks design problem. In: Proceedings of the 7th international workshop on hybrid metaheuristics. Springer, Berlin/Heidelberg, pp 46–61
Glover F, Laguna M (1999) Tabu search. Handbook of combinatorial optimization, 3rd edn. Kluwer Academic Publishers, London
Goldberg DE, Deb K (1990) A comparative analysis of selection schemes used in genetic algorithms. In: Foundations of genetic algorithms (FOGA). Morgan Kaufmann, San Franciso, pp 69–93
Montgomery D (2005) Design and analysis of experiments. Wiley, New York
Moscato P (1989) On evolution, search, optimization, gas and martial arts: towards memetic algorithms. In: Technical report of Caltech concurrent computer programming report, vol 826. California Institute of Technology, Pasadena
Musliu N, Schaerf A, Slany W (2004) Local search for shift design. Eur J Oper Res 153(1):51–64
Musliu N, Schafhauser W, Widl M (2009) A memetic algorithm for a break scheduling problem. In: 8th Metaheuristic international conference, Hamburg
Papadimitriou CH, Steiglitz K (1982) Combinatorial optimization: algorithms and complexity. Prentice Hall, London
Quimper C-G, Rousseau L-M (2010) A large neighbourhood search approach to the multi-activity shift scheduling problem. J Heuristics 16(3):373–391
Rekik M, Cordeau J, Soumis F (2010) Implicit shift scheduling with multiple breaks and work stretch duration restrictions. J Sched 13:49–75
Schafhauser W (2010) TEMPLE—a domain specific language for modeling and solving real-life staff scheduling problems. PhD thesis, Vienna University of Technology, Wien
Softnet (2008) http://www.dbai.tuwien.ac.at/proj/SoftNet/Supervision/Benchmarks/.Accessed 14 March 2014
Tellier P, White G (2006) Generating personnel schedules in an industrial setting using a tabu search algorithm. In: Burke EK, Rudova H (eds) The 5th international conference on the practice and theory of automated timetabling, pp 293–302
Thompson G (1995) Improved implicit modeling of the labor shift scheduling problem. Manag Sci 41(4):595–607
Widl M (2010) Memetic algorithms for break scheduling. Master’s thesis, Vienna University of Technology, Vienna http://www.kr.tuwien.ac.at/staff/widl/publications/Masterthesis.pdf. Accessed 14 March 2014
Widl M, Musliu N (2010) An improved memetic algorithm for break scheduling. In: Hybrid Metaheuristics, vol 6373 of LNCS, pp 133–147
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This work was supported by the Austrian Science Fund (FWF) under grants P24814-N23 and S11409-N23, and by the Vienna Science and Technology Fund (WWTF) under grant ICT10-018.
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Widl, M., Musliu, N. The break scheduling problem: complexity results and practical algorithms. Memetic Comp. 6, 97–112 (2014). https://doi.org/10.1007/s12293-014-0131-0
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DOI: https://doi.org/10.1007/s12293-014-0131-0