1. A Scatter Search Approach to the Nurse Rostering Problem Speaker: Kuo-Hsien Chuang 2009/10/20

2. Introduction GA, PSO, ACO, Scatter Search –the maintenance of a population of solutions –contrast to many other metaheuristics which generally work with one solution, for example SA, TS, and VNS. Solution Quality Solution Diversity

3. The Nurse Rostering Problem and Benchmark Instances Objectives –such as maximising the nurses working preferences and/or minimising wage costs. Benchmark –real world scenarios –http://www.cs.nott.ac.uk/~tec/NRPhttp://www.cs.nott.ac.uk/~tec/NRP –Free software

4. The Nurse Rostering Problem and Benchmark Instances (cont.)

5. Hard Constraint –the cover requirements per shift type for each day, over cover and under cover is not permitted –a nurse may not work more than one shift of the same type on the same day –shifts which require skills are assigned to a nurses with the required skills.

6. The Nurse Rostering Problem and Benchmark Instances (cont.) Soft Constraint –goal –It may be violated but a value will be added in the objective function –a minimisation of a weighted sum of the soft constraints

7. The Scatter Search for Nurse Rostering Problems

8. The Scatter Search for Nurse Rostering Problems (cont.)

16. Experiment

19. 重複執行到 |P| = Size P111P111 多樣性方法 Method 產生子集合 Method 改進方法 Method 結合方法 改進方法 沒有產生 新的解 參考解集合 Update Method RefSet 多樣性方法 Generation Method 改進方法 Method 達到 MaxIter 停止