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## Chapter5 Knowledge Reasoning and Inferencing

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### Lives in India and Southeast Asia. Lion look like tiger. Conclusion Lion has four legs,Eats meat ... elephant (Clyde) IF elephant( x ) THEN mammal( x ) unification: ... – PowerPoint PPT presentation

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Title: Chapter5 Knowledge Reasoning and Inferencing

1
Chapter5 Knowledge Reasoning and Inferencing
• ????? 5 ????????????????????????
• Sasalak Tongkaw

2
???????????????
• Durkin (1994) ???????? ???????????????
???????????????????????????? ????????
??????????????????????????????????????????
• Deductive
• Inductive
• Abductive
• Analogical
• Common-Sense

3
1.Deductive Reasoning
• Rule I an standing in the raingtI will get wet
• Axiom I am standing in the rain
• Conclusion I will get wet

4
2.Inductive Reasoning
• Axiom1 Monkeys in the National Zoo eat bananas
• Axiom2 Monkeys in the Songkhla Zoo eat bananas
• Conclusion All monkeys eat bananas

5
3.Abductive Reasoning
• Rule It is raininggt ground is wet
• Axiom ground is wet
• Conclusion Is it raining?

No may be it wet because of pouring water
6
4.Analogical Reasoning
• Tiger has four legs, Eats meat
• Lives in India and Southeast Asia
• Lion look like tiger
• Conclusion Lion has four legs,Eats meat
• Lives in India and Southeast Asia

7
5.Common-Sense Reasoning
• ?????????? ???????????????????????????????????????
??????????????????? ??????????? common-sense ????
??????????????????????????????????????????????????
???????????

8
Inference techniques
• Modus Ponens
• Hypothethical syllogism
• Modus Tollens
• Resolution

9
Modus Ponens
• If X then Y
• X is True
• Conclusion Y is True

X gt Y X Conclusion Y
10
Hypothethical Syllogism
• If X then Y
• If Y then Z
• Conclusion If X then Z

X gt Y Y gt Z Conclusion XgtZ
11
Modus Tollens
• If A then B
• not B
• Conclusion not A

A gt B B Conclusion A
12
Forward Chaining
• given a set of basic facts, we try to derive a
conclusion from these facts
• example What can we conjecture about Clyde?

IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant (Clyde)
unification find compatible values for
variables
13
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
IF elephant( x ) THEN mammal( x )
elephant (Clyde)
14
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
15
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
IF mammal( x ) THEN animal( x )
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
16
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
17
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal( x )
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
18
Forward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
19
Backward Chaining
• try to find supportive evidence (i.e. facts) for
a hypothesis
• example Is there evidence that Clyde is an
animal?

IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant (Clyde)
unification find compatible values for
variables
20
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal( x ) THEN animal( x )
21
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
22
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
IF elephant( x ) THEN mammal( x )
23
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
24
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
elephant ( x )
25
Backward Chaining Example
IF elephant(x) THEN mammal(x) IF mammal(x) THEN
animal(x) elephant(Clyde)
unification find compatible values for variables
animal(Clyde)
IF mammal(Clyde) THEN animal(Clyde)
IF elephant(Clyde) THEN mammal(Clyde)
elephant (Clyde)
26
Forward vs. Backward Chaining
27
The End of Chapter 5