Information Technology Reference
In-Depth Information
Figure 5. continued
“Does all that is rare is expensive? ”
— 'Teacher' -
give
-
information
(
F
alse
)
“No”
— 'Student' -
say
-
satisfaction
“I understand”
The 'student' understands then where the conflict comes from (Step 3) and revises its base in consequence. The student's
knowledge is now (Step 4):
cheap(x)
→
rare(x)
cheap(x)
→¬
(expensive(x))
_____________________________________________________________________
Figure 6. KB evolution while solving an implication conflict
(a) Step 1
(b) Step 2
(c) Step 3
(d) Step 4
Two other implication types of conflict, harder to detect, may also happen:
•
Let's assume the 'student' owns the two following series of implication Θ and Λ:
Θ = ((
P
1
→
Q
2
)
, (
Q
2
→
Q
3
), …, (
Q
i
−1
→
Q
i
),
Λ = (
Q
i
+1
→
Q
i
+2
), …, (
Q
n
−1
→¬(
P
1
))).
If the 'teacher' gives the knowledge (
Q
i
→
Q
i
+1
) then a conflict arises as from Θ, (
Q
i
→
Q
i
+1
) and Λ
we can deduce ¬(
P
1
)) from
P
1
.
•
Let's assume now the 'student' owns the three following series of implication ∆, Θ and Λ:
∆ = ((P
1
→P
2
), (P
2
→P
3
), …, (P
n
-1
→P
n
)),
Θ = ((
P
1
→
Q
2
)
, (
Q
2
→
Q
3
), …, (
Q
i
−1
→
Q
i
),
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