Family Tree Out Of Local Stack Error

bsplitkids · Dec 3, 2010

I am learning the prolog language and I'm starting with the family tree. When I try to ask different questions I get errors. For instance when I asked was sally the parent of rojai parent(sally,rojai). I got this error message ERROR: Out of local stack
Exception: (310,003) parent(sally, rojai) ? Iooked this error up online and I saw that it had to do with recursion, but I dont know how to fix it. I also got this error when I tried the following:
granddaughter(janae,sheri).
parent(sally,Y).
uncle(desmond,Y).
Does it have something to do with the order of my rules or the parent rule itsself?

The following code:
father(james,sheri).
father(ij,rojai).
father(michael,pam).
father(michael,desmond).
father(michael,tonya).
father(rojai,janae).
father(rojai,imani).
father(desmond,tyson).
father(desmond,miya).
father(desmond,demonica).
father(jason,taylor).
father(jason,bria).
father(X,Y) :- parent(X,Y), male(X).

mother(gwendolyn,sheri).
mother(sally,rojai).
mother(sheri,pam).
mother(sheri,desmond).
mother(sheri,tonya).
mother(pam,janae).
mother(pam,imani).
mother(cheri,tyson).
mother(cheri,miya).
mother(cheri,demonica).
mother(tonya,taylor).
mother(tonya,bria).

male(desmond).
male(james).
male(ij).
male(rojai).
male(tyson).
male(jason).

female(sheri).
female(pam).
female(tonya).
female(janae).
female(imani).
female(miya).
female(demonica).
female(taylor).
female(bria).
female(gwendolyn).
female(cheri).

parent(X,Y) :- father(X,Y).
parent(X,Y) :- mother(X,Y).
mother(X,Y) :- parent(X,Y),female(X).
grandparent(X,Y) :- parent(X,Z),parent(Z,Y).
granddaughter(X,Y) :- female(X),grandparent(Y,X).
sibling(X,Y) :- parent(Z,X),parent(Z,Y),X\==Y.
brother(X,Y) :- sibling(X,Y),male(X),X\==Y.
sister(X,Y) :- sibling(X,Y),female(X),X\==Y.
uncle(X,Y) :- male(X),sibling(X,Z),parent(Z,Y).
aunt(X,Y) :- female(X),sibling(X,Z),parent(Z,Y).
niece(X,Y) :- female(X),sibling(Z,Y),parent(Z,X).

confusedstudent1 · Dec 3, 2010

I think I kinda fixed it.

father(james,sheri).
father(ij,rojai).
father(michael,pam).
father(michael,desmond).
father(michael,tonya).
father(rojai,janae).
father(rojai,imani).
father(desmond,tyson).
father(desmond,miya).
father(desmond,demonica).
father(jason,taylor).
father(jason,bria).
father(X,Y) :- male(X),parent(X,Y).

mother(gwendolyn,sheri).
mother(sally,rojai).
mother(sheri,pam).
mother(sheri,desmond).
mother(sheri,tonya).
mother(pam,janae).
mother(pam,imani).
mother(cheri,tyson).
mother(cheri,miya).
mother(cheri,demonica).
mother(tonya,taylor).
mother(tonya,bria).
mother(X,Y) :- female(X),parent(X,Y).

male(desmond).
male(james).
male(ij).
male(rojai).
male(tyson).
male(jason).

female(sheri).
female(pam).
female(tonya).
female(janae).
female(imani).
female(miya).
female(demonica).
female(taylor).
female(bria).
female(gwendolyn).
female(cheri).

parent(X,Y) :- father(X,Y).
parent(X,Y) :- mother(X,Y).
grandparent(X,Y) :- parent(X,Z),parent(Z,Y).
granddaughter(X,Y) :- female(X),grandparent(Y,X).
sibling(X,Y) :- parent(Z,X),parent(Z,Y),X\==Y.
brother(X,Y) :- sibling(X,Y),male(X),X\==Y.
sister(X,Y) :- sibling(X,Y),female(X),X\==Y.
uncle(X,Y) :- male(X),sibling(X,Z),parent(Z,Y).
aunt(X,Y) :- female(X),sibling(X,Z),parent(Z,Y).
niece(X,Y) :- female(X),sibling(Z,Y),parent(Z,X).

kahleen · Dec 3, 2010

What you need to do is remove these 2 clauses:

Code:

father(X, Y) :- parent(X, Y), male(X).

mother(X, Y) :- parent(X, Y), female(X).

You define some 'father' clauses, you define some 'mother' clauses, the 'father' clause uses the 'parent' clause and the 'parent' clause uses the 'father' clause again. While this is not a conceptual problem, it is a conceptual problem here in your code because you just make these calls with the same parameters, so Prolog will just go in a recursive loop without anything to get him out.

Code:

parent(X, Y) :- father(X, Y).
father(X, Y) :- parent(X, Y), ...

See the problem? When you call parent(sally, rojai) Prolog will call father(sally, rojai) which calls parent(sally, rojai) again and so on.

'father' and 'mother' are defined with concrete facts, so you don't need to define them further using 'parent', because 'parent' is defined in terms of 'father' and 'mother'.

There are still some minor problems in your code, but your main problem is solved by removing those 2 clauses

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Family Tree Out Of Local Stack Error

bsplitkids

Programmer

confusedstudent1

Programmer

kahleen

Programmer

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