% More advanced predicates for handling family relationships.
% This includes predicates that are used as commands to assert
% family relationships that record births and marriages.
% This predicate is changes parent, male, and female: birth(Mother, Father, Child, Gender).
% This predicate is changes parent: marry(Mother, Father).
:-dynamic(parent/2).
:-dynamic(male/1).
:-dynamic(female/1).

:-style_check(-singleton).

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

sister(X,Y):-parent(Z,X),parent(Z,Y),female(X),X\=Y.
brother(X,Y):-parent(Z,X),parent(Z,Y),male(X),X\=Y.

sibling(X,Y):-sister(X,Y).
sibling(X,Y):-brother(X,Y).

grandparent(X,Y):-parent(X,Z),parent(Z,Y).

grandfather(X,Y):-male(X),grandparent(X,Y).
grandmother(X,Y):-female(X),grandparent(X,Y).
grandchild(X,Y):-grandparent(Y,X).

child(X,Y):-parent(Y,X).
son(X,Y):-child(X,Y),male(X).
daughter(X,Y):-child(X,Y),female(X).

uncle(X,Y):-brother(X,P),parent(P,Y).
aunt(X,Y):-sister(X,P),parent(P,Y).

grandson(X,Y):-son(X,P),child(P,Y).
granddaughter(X,Y):-daughter(X,P),child(P).
% married(X,Y):-parent(X,Z), parent(Y,Z), X\=Y.
% married(X,Y):-married(Y, X), !.

wife(X,Y):-married(X,Y),female(X).
husband(X,Y):-married(X,Y),male(Y).

birth(Mother, Father, Child, son):-asserta(parent(Mother, Child)),
	asserta(parent(Father, Child)),
	asserta(male(Child)).

birth(Mother, Father, Child, daughter):-asserta(parent(Mother, Child)),
	asserta(parent(Father, Child)),
	asserta(female(Child)).
birth(Mother, Father, Child):-asserta(parent(Mother, Child)),
	asserta(parent(Father, Child)).

adopt(Person, []).
adopt(Person, [Child|Rest]):-asserta(parent(Person, Child)),
	adopt(Person, Rest).

marry(Man, Woman):-asserta(married(Woman, Man)),
	findchildren(Man, Hiskids), adopt(Woman, Hiskids),
	findchildren(Woman,Herkids), adopt(Man, Herkids).

findchildren(Person, Children):-findall(X,parent(Person,X),Children).

go:-write('Input a fact with a period(input ok at end): '), 
	read(Term), 
	( Term=ok , !;
	  assert(Term), 
	  Term=..[Functor|_], listing(Functor),
	  go
	).