1. Stephen Chen York University
A Little Respect (for the Role of Common Components in Heuristic Search)
Stephen Chen
York University

2. Heuristic Search Search Operators Control Strategies August 21, 2006
IFIP WCC 2006

3. An Obvious Failing
Point search operators do not have historical information!
Most research focuses on the control strategies
August 21, 2006
IFIP WCC 2006

4. Search Operator Strategies
What can be improved?
What is worth keeping?
Most search operators focus on what they change, not what they keep
August 21, 2006
IFIP WCC 2006

5. What Should Search Operators Keep?
Would like to keep “above-average” components of existing solutions and change their “below-average” components
Use Commonality Hypothesis to identify “above-average” components
August 21, 2006
IFIP WCC 2006

6. The Commonality Hypothesis
Schemata common to above-average solutions are above average
Search operators should keep common components and change uncommon components
August 21, 2006
IFIP WCC 2006

7. A Simple Example Parent 1 1 1 1 0 0 1 0 1 1 1
Common
Uncommon
Uncommon
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IFIP WCC 2006

8. TSP Nearest Neighbour Tours
August 21, 2006
IFIP WCC 2006

9. Common and Uncommon Components
August 21, 2006
IFIP WCC 2006

10. Random Local Minima
August 21, 2006
IFIP WCC 2006

11. Simulated Annealing
August 21, 2006
IFIP WCC 2006

12. Summary Random search space, random search strategy
All the intelligence of simulated annealing is in the control strategy
August 21, 2006
IFIP WCC 2006

13. Distribution of Local Minima (Boese)
Length
Average distance from other local minima
August 21, 2006
IFIP WCC 2006

14. “Big-Valley” – Globally Convex
August 21, 2006
IFIP WCC 2006

15. “Directed” Simulated Annealing
August 21, 2006
IFIP WCC 2006

16. Coordination with Common Components
August 21, 2006
IFIP WCC 2006

17. TSP Results Instance BaseSA SAGA dsj1000 4.54 2.27 d1291 8.87 3.12
fl1577
6.47
0.64
August 21, 2006
IFIP WCC 2006

18. Summary Globally convex search space, “respectful” search operator
Add some intelligence to the search operator
August 21, 2006
IFIP WCC 2006

19. Conclusion
The preservation of common components can improve the performance of heuristic search procedures in globally convex search spaces
August 21, 2006
IFIP WCC 2006