prolog皇室树

Question

我的问题类似于此处提出的问题：determine the old line of succession prolog和此Prolog - recursing down family tree 正如所说的解决方案并不是我真正想要的，有谁能提出如何解决以下问题的想法？谢谢！

事实：

male(charles).
male(william).
male(peter).
male(henry).
male(andrew).
male(edward).


female(elizabeth).
female(anne).
female(zara).
female(eugenie).

parent(elizabeth,charles).
parent(elizabeth,anne).
parent(elizabeth,andrew).
parent(elizabeth,edward).
parent(charles,william).
parent(charles,henry).
parent(anne,peter).
parent(anne,zara).
parent(andrew,eugenie).

规则：

son(X,Y) :- parent(Y,X), male(X).
daughter(X,Y) :- parent(Y,X), female(X).    
successor(X,Y):- (son(X,Z);daughter(X,Z)) , (Y=Z;successor(Z,Y)). 

查询后继者（X，Y）时到目前为止的结果。

 X = charles,
 Y = elizabeth ;
 X = andrew,
 Y = elizabeth ;
 X = edward,
 Y = elizabeth ;
 X = william,
 Y = charles ;
 X = william,
 Y = elizabeth ;
 X = henry,
 Y = charles ;
 X = henry,
 Y = elizabeth ;
 X = peter,
 Y = anne ;
 X = peter,
 Y = elizabeth ;
 X = anne,
 Y = elizabeth ;
 X = zara,
 Y = anne ;
 X = zara,
 Y = elizabeth ;

我想展示的实际结果是查尔斯＆＃39;家人，安德鲁的家人，爱德华的家人和最后安妮的家人，但安妮的儿子首先出现。我猜这是因为儿子（X，Y）规则首先执行并找到所有匹配，并且后继（X，Y）存在问题。有没有办法让我在找到安妮后执行它？谢谢！

实际答案可能是

 X = charles,
 Y = elizabeth;
 X = william,
 Y = charles;
 X = william,
 Y = elizabeth ;
 X = henry,
 Y = charles ;
 X = henry,
 Y = elizabeth ;

 X = andrew,
 Y = elizabeth ;
 X = eugenie,
 Y = andrew ;
 X = eugenie,
 Y = elizabeth ;

 X = edward,
 Y = elizabeth ;


 X = anne,
 Y = elizabeth ;
 X = peter,
 Y = anne ;
 X = peter,
 Y = elizabeth ;
 X = zara,
 Y = anne ;
 X = zara,
 Y = elizabeth ;