1. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering CSCE 580 Artificial Intelligence Problem Spaces and Search Fall 2008 Jingsong Wang wang82@engr.sc.edu

2. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstraction and Generality in Java The Interaction between AI theory and program architecture –Implementation of search strategies Generality and reuse –Abstraction mechanisms and design patterns

3. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Search Algorithms Uninformed algorithms: –Depth-first search (DFS) –Breadth-first search (BFS) –… Informed algorithms –Best-first search –…

4. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Search Algorithms Model the structure of a problem graphically as a state—space Elements defining a state-space: –A formal representation of possible states of a problem solution –Operators for generating new states from a given state –Some way of recognizing a goal state –A starting state of the problem, represented as the root of the graph

5. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

6. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

7. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Search Algorithms DFS – stack BFS – queue Best-first search – priority queue –Heuristic rank –sorted

8. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstracting Problem States The separation of representation and control –States and search engines Goal: to define an abstract representation of problems states that supports the general search algorithm and can be easily specialized through the mechanism of class inheritance

9. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstracting Problem States

10. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstracting Problem States Abstract class

11. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstracting Problem States Interface

12. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Abstracting Problem States Java’s generic –Collection-Type

13. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

14. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

15. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Traversing the Problem Space Implementation of search itself –Define the list of states and the mechanisms for moving through them in search

16. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

17. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

18. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

19. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering

20. UNIVERSITY OF SOUTH CAROLINA Department of Computer Science and Engineering Putting the Framework to Use See the code in Eclipse