%h(State, EstimatedValue)
% Estimated distance to achive Goal.
:-use_module(library(sets)).

h(S, E):-
		bb_get(fictiveGoal, G),
		relax(S, G, E).
%    write(G-S-E),nl.

relax(_, [], 0):-!.
relax(S, G, E):-
    		subtract(G, S, Delta),
		setof(P, relax_step(S, P), RS),
		sort(S, S1), sort(RS, RS1), % I am not sure if this is necessary
		ord_union([S1|RS1], NS),
    		relax(NS, Delta, NE),
		length(Delta, LD),
		E is LD+NE.

relax_step(State, PE) :-
		get_action(A),	get_precondition(A, P),
		mysubset(P, State), 
		get_positiv_effect(A, PE1), sort(PE1, PE).