In a database, a rule is defined as (P1 and P2) or P3 ? R1(0.8) and R2(0.3),…
2022
In a database, a rule is defined as (P1 and P2) or P3 ? R1(0.8) and R2(0.3), where P1, P2. P3 are premises and R1. R2 are conclusions of rules with certainty factors (CF) 0.8 and 0.3 respectively. If any running program has produced P1, P2, P3 with CF as 0.5,0.8, 0.2 respectively. find the CF of results on the basis of premises.
- A.
CF(R1=0.8),CF(R2=0.3)
- B.
CF(R1=0.40),CF(R2=0.15)
- C.
CF(R1=0.15),CF(R2=0.35)
- D.
CF(R1=0.8),CF(R2=0.35)
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Correct answer: B
Key idea: compute the antecedent certainty using min for AND and max for OR, then multiply the antecedent CF by each rule's CF.
Given: CF(P1) = 0.5, CF(P2) = 0.8, CF(P3) = 0.2; rule strengths: CF(R1) = 0.8, CF(R2) = 0.3.
Compute the AND of P1 and P2: CF(P1 and P2) = min(0.5, 0.8) = 0.5.
Compute the OR with P3: CF((P1 and P2) or P3) = max(0.5, 0.2) = 0.5.
Apply rule strengths by multiplying the antecedent CF by each rule CF:
CF(R1) = 0.8 * 0.5 = 0.40
CF(R2) = 0.3 * 0.5 = 0.15
Final result: CF(R1) = 0.40, CF(R2) = 0.15.
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