Prolog - 尝试解决文本难题

Posted 2023-05-08

【中文标题】Prolog - 尝试解决文本难题

【英文标题】：Prolog - trying to solve textual puzzle

【发布时间】：2013-08-19 19:42:38

【问题描述】：

我目前正在尝试学习一点 Prolog。作为一个练习，我试图解决以下谜题：

给出这些规则：

*Every person that has neither a car nor a plane, has a bike.
*Every person that doesn't have a plane but has a bike, has a car
*Every person that doesn't have a plane but has a car, has a truck
*Every person that doesn't have a truck but has a boat, doesn't have a plane
*Every person that doesn't have a boat but has a plane, doesn't have a car

现在有四个人：

*Person1 doesn't have a car but has a boat
*Person2 doesn't have a boat but has a plane
*Person3 doesn't have a plane but has a bike
*Person4 doesn't have a bike but has a car

谁没有卡车？

到目前为止，我想出的是：

doesnthave(car,pa).
has(boat,pa).
doesnthave(boat,pb).
has(plane,pb).
doesnthave(plane,pc).
has(bike,pc).
doesnthave(bike,pd).
has(car,pd).

has(bike,X) :- doesnthave(car,X),doesnthave(plane,X).
has(car,X) :- doesnthave(plane,X),has(bike,X).
has(truck,X) :- doesnthave(plane,X),has(car,X).
doesnthave(plane,X) :- doesnthave(truck,X),has(boat,X).
doesnthave(car,X) :- doesnthave(boat,X),has(plane,X).

现在这似乎还不够。或者这不是prolog中解决此类谜题的方法吗？

编辑：前两个陈述似乎是矛盾的。它们共同产生：每个既没有汽车也没有飞机的人都有汽车。我不确定是否有合理的解决方案。

【参考方案1】：

不确定这个解决方案，但更简单的知识表示肯定会有所帮助：

has(car,   pa, n). has(boat,  pa, y).
has(boat,  pb, n). has(plane, pb, y).
has(plane, pc, n). has(bike,  pc, y).
has(bike,  pd, n). has(car,   pd, y).

has(bike,  X,  y) :- has(car,   X, n), has(plane, X, n).
has(car,   X,  y) :- has(plane, X, n), has(bike,  X, y).
has(truck, X,  y) :- has(plane, X, n), has(car,   X, y).
has(plane, X,  n) :- has(truck, X, n), has(boat,  X, y).
has(car,   X,  n) :- has(boat,  X, n), has(plane, X, y).

现在我们可以查询所有权是什么（注意这是一对多的关系）

?- setof((P,T,R), has(T,P,R), L), maplist(writeln, L).
pa,boat,y
pa,car,n
pb,boat,n
pb,car,n
pb,plane,y
pc,bike,y
pc,car,y
pc,plane,n
pc,truck,y
pd,bike,n
pd,car,y
L = [ (pa, boat, y), (pa, car, n), (pb, boat, n), (pb, car, n), (pb, plane, y), (pc, bike, y), (pc, car, y), (pc, ..., ...), (..., ...)|...].

注意，我将Person 放在Transport 之前，然后我们可以直观地检查结果...

看来解决办法是三重...

【讨论】：

事实证明，前两个陈述存在矛盾。它们共同产生：每个既没有汽车也没有飞机的人都有汽车。