P(S | C, I) = P(S | I)
(例)
P(V | U) P(V | ¬U) P(¬V | U) P(¬V | ¬U)
P(Income) = P(Income|Bonus)P(Bonus) + P(Income|¬Bonus)P(¬Bonus) = 0.8*0.6 + 0.3*0.4 = 0.6 P(Travel) = P(Travel|Income)P(Income) + P(Travel|¬Income)P(¬Income) = 0.2*0.6 + 0.5*0.4 = 0.32(ベイズネットワークの各ノードの確率の計算)
P(Travel|Airplane) = P(Airplane|Travel)P(Travel)/P(Airplane) = 0.95*0.32/0.712 ≒ 0.427
P(Income|Airplane) = P(Airplane|Income)P(Income)/P(Airplane) = (P(Airplane|Travel)P(Travel|Income))P(Income)/P(Airplane)+ (P(Airplane|¬Travel)P(¬Travel|Income))P(Income)/P(Airplane) ≒ (0.95*0.2 + 0.8*0.6)*0.6/0.712 ≒ 0.565
P(Party|Airplane) = P(Party|Income)P(Income|Airplane) + P(Party | ¬Income)P(¬Income|Airplane) ≒ 0.7*0.565 + 0.1*0.435 ≒ 0.439(「Airplane = True」が与えられた時の各ノードの確 率)