(x){~Like(Tony, x)∨~Like(Mike, x)} =>~Like(Tony, x)∨~Like(Mike, x) Р(8) (x){~Like(Tony, x)→Like(Mike, x)} = (x){Like(Tony, x)∨Like(Mike, x)} => Like(Tony, x)∨Like(Mike, x)Р(9) Like(Tony, Snow) (10) Like(Tony, Rain) Р目标取反:Р~(x){Alpine(x)∧Alpinist(x)∧~Skier(x)}Р= (x){~Alpine(x)∨~Alpinist(x)∨Skier(x)} Р=>~Alpine(x)∨~Alpinist(x)∨Skier(x)Р经变量换名后,得到子句集: Р{Alpine(Tony), Alpine(Mike), Alpine(John), ~Alpine(x1)∨Skier(x1)∨Alpinist(x1), ~Alpinist(x2)∨~Like(x2, Rain), Like(x3, Snow)∨~ Skier(x3), ~Like(Tony, x4)∨~Like(Mike, x4), Like(Tony, x5)∨Like(Mike, x5), Like(Tony, Snow), Like(Tony, Rain), ~Alpine(x)∨~Alpinist(x)∨Skier(x)} 归结树如下:Р4.10答:基于规则的演绎推理可分为正向演绎推理、反向演绎推理和正反向混合演绎推理。Р在正向演绎推理中,作为F规则用的蕴含式对事实的总数据库进行操作运算,直至得到Р该目标公式的一个终止条件为止。事实目标公式Р在反向演绎推理中,作为B规则用的蕴含式对目标的总数据库进行操作运算,直至得到Р包含这些事实的终止条件为止。目标公式事实Р4.11答:
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