1. Lecture 3-1CS251: Intro to AI/Lisp II Cognition and Planning A Cognitive Model of Planning, by Hayes-Roth & Hayes-Roth

2. Lecture 3-1CS251: Intro to AI/Lisp II Blackboard systems First system: HEARSAY-II (1971-76) –Understood queries about a database of computer science abstracts Later: HASP (1973-1975) –Domain: Ocean surveillance –Task: Interpreting continuous passive sonar

3. Lecture 3-1CS251: Intro to AI/Lisp II Reasoning in Order Forward chaining –OPS5 Backward chaining –MYCIN Opportunistic –Do whatever works best

4. Lecture 3-1CS251: Intro to AI/Lisp II BB Organization Solution space is broken down into multiple application-dependent hierarchies –Any kind of hierarchy is okay –Abstraction, part-of, … Domain knowledge distributed among knowledge sources –Each source has partial solution

5. Lecture 3-1CS251: Intro to AI/Lisp II The Jigsaw Analogy How is this opportunistic? Flow of data? Control structure?

6. Lecture 3-1CS251: Intro to AI/Lisp II

7. Lecture 3-1CS251: Intro to AI/Lisp II

8. Lecture 3-1CS251: Intro to AI/Lisp II

9. Lecture 3-1CS251: Intro to AI/Lisp II

10. Lecture 3-1CS251: Intro to AI/Lisp II

11. Lecture 3-1CS251: Intro to AI/Lisp II Finding Koalas

12. Lecture 3-1CS251: Intro to AI/Lisp II The Koala Blackboard Koala Head/Torso Limbs Regions Lines Behavior KS Body KS Leg KS Color KS

13. Lecture 3-1CS251: Intro to AI/Lisp II Knowledge Sources Each source’s objective is to contribute information that will lead to the solution Sources are procedures, sets or rules Only modify the blackboard, which can only be modified by the sources Each sources must recognize when it can contribute

14. Lecture 3-1CS251: Intro to AI/Lisp II The Blackboard Purpose: Hold computational & solution state data needed/created by KS’s Made of:Objects in solution space –Objects and their properties defined the solution space –Object relationships in named links Hierarchical organization by level of analysis –Multiple hierarchies are possible

15. Lecture 3-1CS251: Intro to AI/Lisp II Controlling the Computation KS’s respond opportunistically to changes in the blackboard Set of control modules monitor BB Focus of attention decides what to work with next –Blackboard objects (Event scheduling) –Knowledge sources (Knowledge scheduling)

16. Lecture 3-1CS251: Intro to AI/Lisp II Five Levels of the Blackboard Plan Knowledge base Plan abstraction Meta-plan Executive