family(family_member(oleg, barmin, birth_date(6, 1, 98), false), family_member(kate, barmin, birth_date(1, 10, 97), true),
children(family_member(vasy, barmin, birth_date(5, 12, 07), true))).
family(family_member(artem, kudinov, birth_date(6, 1, 57), true), family_member(ann, kudinov, birth_date(1, 10, 67), false),
children(family_member(julia, barmin, birth_date(5, 12, 88), false))).
family(family_member(kola, avramov, birth_date(6, 1, 57), false), family_member(nastya, avramov, birth_date(1, 10, 67), false),
children(family_member(masha, avramov, birth_date(5, 12, 88), false),family_member(fedya, avramov, birth_date(5, 12, 88), false))).
family(family_member(ivan, petrov, birth_date(6, 1, 57), true), family_member(daria, petrov, birth_date(1, 10, 67), false),
children(family_member(a00000000, petrov, birth_date(5, 12, 88), false),family_member(warihaerh, petrov, birth_date(5, 12, 88), false),
family_member(b00000000, petrov, birth_date(5, 12, 88), false))).
family(family_member(ivan, ivanov, birth_date(6, 1, 57), true), family_member(daria, ivanov, birth_date(1, 10, 67), false),
children(family_member(a00000000, ivanov, birth_date(5, 12, 88), false),family_member(warihaerh, ivanov, birth_date(5, 12, 88), false),
family_member(orihthth, ivanov, birth_date(5, 12, 88), false), family_member(shgsgh, ivanov, birth_date(5, 12, 88), false))).
familyWifeWorkFalse(Y) :-
Y = family_member(_, _, _, false),
family(_, family_member(_, _, _, false), _).
oneChildrenMan(X) :-
family(X, _, children(_)).
twoChildrenMan(X) :-
family(X, _, children(_, _)).
moreTwoChildrenMan(X) :-
\+oneChildrenMan(X),
\+twoChildrenMan(X),
family(X, _, _).
Hello everyone! I need help with my prolog task. I have several families, where first variable is a husbend, second one is a wifes and third one is children. I need to create a rule, which will output families with 3 and more children. I have created rules with output of one and two children and than try to exclude them in the third rule. But i got:
?- moreTwoChildrenMan(X).
false.
I have been tring to complete the task my self for several days, but i didnt get any result. Is there any idea how to do this?
The issue with your moreTwoChildrenMan/1 predicate is that you use Prolog's backtracking incorrectly.
The goal negation operator \+ forces the execution mechanism of Prolog search for alternative solutions for the previous goal, and in the code of moreTwoChildrenMan/1 there is no goal prior to oneChildrenMan(X). This is why the predicate fails.
But if you just move the goal family(X, _, _) before the goal oneChildrenMan(X) it will give you the desired result, since now the execution will backtrack on solutions for family(X, _, _):
moreTwoChildrenMan(X) :-
family(X, _, _), % find some family member X
\+ oneChildrenMan(X), % filter out those with one child
\+ twoChildrenMan(X). % filter out those with two children