Prolog

• 事实
• 规则
• 查询

起步

likes(wallace, cheese).likes(grommit, cheese).likes(wendolene, sheep).friend(X,Y) : - \+(X = Y), likes(X, Z), likes(Y, Z).

前面三行定义事实 最后一行定义规则

pl会通过根据规则并且扫描知识的方式得出yes或no的回答