Constraint Programming can be used to solve many problems and this thesis is about getting an overview on the usage of Constraint Programming for Constraint Satisfaction Problems, both interactive and explorative. Many problems can be mathematically modeled as a Constraint Satisfaction Problem but this thesis will focus on the Nurse Rostering Problem since it is a well-studied area. The problem when creating a schedule for nurses is that it can easily be over-constrained and a solution could be hard to find. This thesis will investigate whether if Constraint Programming is a good technique for solving the Nurse Rostering Problem but also if user interaction is considered when solving the problem. The method for this is a literature study where a number of research articles has been reviewed and categorized, and resulted in 27 different kinds of sources that were used. The conclusion is that there exists better ways to solve these problems than the use of pure Constraint Programming. To answer the second part of the thesis, it seems like the solution for the problem is the main focus and therefore is user interaction something that is given less attention.

Šioje disertacijoje nagrinėjamas sveikatos priežiūros įstaigos darbuotojų darbų grafikų optimizavimo uždavinys, kuris formuluojamas ir sprendžiamas, remiantis vienos didžiausių Lietuvos sveikatos priežiūros įstaigų, realiais duomenimis. Disertacijoje apžvelgiami darbų grafikų optimizavimo uždaviniai bei jų sprendimo metodai, atlikta naujausių šaltinių, tiriančių panašius uždavinius, analizė. Antrame skyriuje nagrinėjamasis darbų grafikų optimizavimo uždavinys suformuluotas matematiškai. Pateikiamos dvi formuluotės: vienakriterio ir daugiakriterio optimizavimo uždavinio. Aprašomos sąlygos, kurias turi tenkinti sudaromasis darbų grafikas. Trečiajame skyriuje nagrinėjami metodai, tiek vienakriteriams, tiek daugiakriteriams uždaviniams spręsti. Pasiūlytas naujas metodas, kuris efektyviau nei kiti nagrinėti metodai sprendžia šioje disertacijoje suformuluotą uždavinį. Ketvirtame skyriuje pateikiami pasiūlyto metodo eksperimentinio tyrimo rezultatai. Pirmoje skyriaus dalyje analizuojami rezultatai gauti, sprendžiant vienakriterį optimizavimo uždavinį, o antroje dalyje – daugiakriterį optimizavimo uždavinį. Disertacijos tyrimų rezultatai buvo pristatyti respublikinėje konferencijoje ir trijose tarptautinėse konferencijose bei publikuoti trijuose mokslo žurnaluose. / In this dissertation nurse rostering problem is investigated. The formulation of the problem is based on real-world data of one of the largest healthcare centers in Lithuania. Most recent publications that tackle the nurse rostering problem and the methods for solving the nurse rostering problem are reviewed in this dissertation. The mathematical formulation of the single objective and the multi-objective nurse rostering problem is presented and the requirements for the roster are described in the second chapter. In the third chapter, the methods for solving the single objective and the multi-objective nurse rostering problem are described. A new method for solving the single objective and the multi-objective nurse rostering problem is proposed in the third chapter. In the fourth chapter, the experimental results of our proposed method are introduced. In the first section of this chapter, the results gathered solving single-objective optimization problem are analyzed, and in the second section of this chapter, the results gathered solving multi-objective optimization problem are analyzed. Dissertation research results were presented at one national conference and three international conferences and published in three scientific journals.

In the dissertation the nurse rostering problem is investigated. The formulation of the problem is based on real-world data of one of the largest healthcare centers in Lithuania. Most recent publications that tackle the nurse rostering problem and the methods for solving the nurse rostering problem are reviewed, the mathematical formulation of the single objective and the multi-objective nurse rostering problem is presented, the requirements for the roster are described and a new method for solving the single objective and the multi-objective nurse rostering problem is proposed in this dissertation. / Disertacijoje nagrinėjamas sveikatos priežiūros įstaigos darbuotojų darbų grafikų optimizavimo uždavinys, kuris formuluojamas ir sprendžiamas, remiantis vienos didžiausių Lietuvos sveikatos priežiūros įstaigų, realiais duomenimis. Disertacijoje apžvelgiami darbų grafikų optimizavimo uždaviniai bei jų sprendimo metodai. Pateikiama nagrinėjamo darbų grafikų vienakriterio ir daugiakriterio optimizavimo uždavinių matematinės formuluotės. Aprašomos sąlygos, kurias turi tenkinti sudaromasis darbų grafikas. Nagrinėjami metodai, tiek vienakriteriams, tiek daugiakriteriams darbų grafikų optimizavimo uždaviniams spręsti. Pasiūlytas naujas metodas, kuris yra efektyvesnis nei kiti nagrinėti metodai sprendžiant disertacijoje suformuluotą uždavinį.

Numerous studies have been done in the area of nurse scheduling, since this is a complex area with a lot of aspects that has to be taken into account. An interesting but little studied subject is how the requirements for the scheduling affect the possibility to construct a feasible schedule, or how the requirements affect the quality of the schedule. Of special interest is the effect of the composition of the workforce and of the change in scheduling rules. What is missing is results showing which composition and changes that are possible, and if so what is needed to be able to follow through with them. The changes tested in our simulation study are changes that is up for discussion at many wards in Sweden today, with topics such as split shifts and high part-time work percentages within the staff. In order to simulate various scheduling requirements and changes, an integer linear model for creating nurse schedules is developed. The results provide some insight into the dependence between scheduling requirements and the resulting schedules. In particular our simulation results indicate that there is an inherent conflict between high part-time work percentages and split or long work shifts. Our results can be used as a basis for future research on these topics in the area of nurse scheduling.