#domain fraction(A,B).

fraction(1,1).
fraction(1,2).
fraction(1,3).
fraction(1,4).
fraction(1,5).
fraction(1,6).
fraction(1,7).
fraction(1,8).
fraction(1,9).
fraction(1,12).
fraction(1,24).
fraction(1,27).
fraction(1,36).
fraction(A,B) :- tag(P,source), target_value(P,A,B).

divide(f(A,B),S,f(A/S,B)) :- A #mod S == 0.
divide(f(A,B),S,f(A,B*S)) :- A #mod S != 0.

value(P,A,B) :- tag(P,source), target_value(P,A,B).

value(P2,Ap,Bp) :-
	tag(P2,divider),
	edge(P1,P2),
	value(P1,A,B),
	divider_outs(P2,S),
	divide(f(A,B),S,f(Ap,Bp)).

value(P2,A,B) :-
	tag(P2,target),
	edge(P1,P2),
	value(P1,A,B).

:- tag(P,target), target_value(P,A,B), not value(P,A,B).

#show value/3.