family.pl

ｐｒｏｌｏｇ样例

female(ann).
female(cathy).
female(lisa).
female(lora).
female(mary).
female(rose).
female(susan).

male(charles).
male(david).
male(fred).
male(george).
male(ian).
male(joe).
male(john).
male(paul).
male(peter).

mother_of(john,ann).
mother_of(mary,ann).
mother_of(cathy,ann).
mother_of(peter,mary).
mother_of(paul,mary).
mother_of(charles,cathy).
mother_of(susan,cathy).
mother_of(george,lora).
mother_of(ian,lora).
mother_of(lisa,rose).

father_of(john,fred).
father_of(mary,fred).
father_of(cathy,fred).
father_of(peter,joe).
father_of(paul,joe).
father_of(charles,david).
father_of(susan,david).
father_of(george,paul).
father_of(ian,paul).
father_of(lisa,charles).

parents(Child,Mother,Father) :- 
   mother_of(Child,Mother),
   father_of(Child,Father).

sisters(X,Y) :- female(X), female(Y),
                X \= Y,
                parents(X,M,F),
                parents(Y,M,F).

is_grandfather(G) :- father_of(X,G),
                     (mother_of(_,X); father_of(_,X)).

ancestor_of(P,A) :- mother_of(P,A).
ancestor_of(P,A) :- father_of(P,A).
ancestor_of(P,A) :- mother_of(P,M), ancestor_of(M,A).
ancestor_of(P,A) :- father_of(P,M), ancestor_of(M,A).

ancestors_of(P,As) :- bagof(A,ancestor_of(P,A),As).

descendants_of(P,Ds) :- bagof(D,ancestor_of(D,P),Ds).

is_grandmother(G) :- mother_of(X,G),
                     (mother_of(_,X); father_of(_,X)).

% inferior implementation of grandparents/0 returning multiple instances ...
% grandparents :- (is_grandmother(G);is_grandfather(G)), write(G), nl, fail.
% grandparents.

grandparents :- setof(G,(is_grandmother(G); is_grandfather(G)),Gs),
                writelist(Gs).

writelist([]).
writelist([H|T]) :- write(H), write(', '), writelist(T).