Turban Chapter 13 section 3 Inferencing with Rules: Forward and Backward Chaining

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Turban Chapter 13 section 3Inferencing with
Rules Forward and Backward Chaining

• Rule IF A (is true)
• THEN B (is the case)
• IF Premise
• THEN Assertion (or conclusion)
• Pattern Matching
• Is A true?
• Has it even been set?
• If not, how is it set?

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Forward Chaining Data driven

• Flying from Denver to Tokyo
• Flights leaving Denver Destinations
• Are any destinations Tokyo?
• If not, from those non Tokyo dests, what flights
  leave?
• Which of those go to Tokyo?

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Backward Chaining Goal Driven

• Flying to Tokyo from Denver
• What flights arrive in Tokyo
• Do any originate in Denver
• If not, for each origination, what flights end
  there?
• And where do they originate (Do any originate in
  Denver)
• .

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Chaining rule linking

• Forward Chaining
• We have a situation
• Search rules for premises that match situation
• Forward chain with conclusion(s) as premise(s)
• Backward
• We know the condition or goal
• Rules with conclusions that match goal
• What other rules have conclusions that match
  those rules premises?

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Represent the Knowledge (1) Mowing Henry was
asked to explain how he decides whether to cut
the grass.

•  If the grass needs cutting, and I am able to cut
  it, then I do. It only needs to be cut during
  the growing season in the summer, when it gets
  too long (more than 4 inches). However, Im not
  always able to cut the grass even when it needs
  it. Sometimes I dont feel well enough to cut
  the grass And, of course, the equipment has to
  be working - it cant be broken or out of gas.
  Also, the conditions have to be right it has to
  be good weather, and I can only cut the grass in
  the middle of the day, so the neighbors dont
  complain about noise. If the grass needs cutting
  and the conditions are right, but Im not able to
  cut the grass, I might find out if anyone else
  can cut the lawn. If they can, then Ill get
  them to do it.

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Represent the Knowledge (2)Dependency Tables
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Represent the Knowledge (3)Dependency Diagrams
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How to dependency diagrams