1. CSE 4705 Artificial Intelligence
Jinbo Bi
Department of Computer Science & Engineering

2. Logic Agents - the forth component AIMA – Chapter 7

3. Knowledge-based agents Wumpus world An introduction to logic
Last two lectures
Knowledge-based agents
Wumpus world
An introduction to logic
Inference, validity, equivalence and satifiability
Propositional logic

4. A key semantic relation: entailment

5. Inference procedures

6. Validity and satisfiability

7. Proof methods for propositional logic

8. Proof methods

9. Review known logical equivalences

10. Review known rules of inference

11. A rule of inference - resolution

12. Resolution

13. Conversion to CNF: general procedure

14. Validity and satisfiability

15. Resolution algorithm

16. Resolution algorithm

17. Resolution example

18. Resolution: The wumpus world

19. Resolution: The wumpus world
Add to KB the following:
observe
By Modus Ponens, we have
We cannot determine if (2,2) and (3,1) will have pit, so we go back to (1,1)

20. Resolution: The wumpus world
Because
, (1,2) is safe to move to.
Then, we observe
By contrapositive
By Modus Ponens
and

21. Resolution: The wumpus world
Our first application of resolution
Because early on, we have
Now, we have
By resolution,
Early on, we also know
By resolution,

22. Resolution: The wumpus world
In-class practice:
Determine if (2,2) should have the wumpus ?

23. The WalkSAT algorithm

24. The WalkSAT algorithm

25. Hard satisfiability problems

26. Hard satisfiability problems

27. Performance of WalkSAT

28. Encoding Wumpus in propositional logic

29. A glance at the Wumpus agent

30. Expressiveness limitation

31. Forward and backward chaining

32. Forward chaining

33. Forward chaining algorithm

34. Forward chaining example

35. Forward chaining example

36. Proof of completeness

37. Backward chaining

38. Backward chaining example

39. Backward chaining example

40. Backward chaining example

41. Backward chaining example

42. Forward vs. backward chaining

43. Questions?

44. Student Evaluation of Teaching
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