type rank(node, int, float).
type calcRank(node, int, sum float).
type persistent numPages(node, int).
type numLinks(node, sum int).

const damping = 0.85.
const num_iterations = 4.
% extern float to_float(int).
% extern float float_abs(float).

rank(A, 0, 1.0 / to_float(T)) :- numPages(A, T).
rank(A, I, V) :-
	calcRank(A, I, T),
	Before = I - 1,
	rank(A, Before, VOld),
	V = damping + (1.0 - damping) * T,
	I =< num_iterations.

% //float_abs((damping + (1.0 - damping) * T) - VOld) > 0.001.

calcRank(A, I + 1, O / to_float(C)) :-
	edge(B, A),
	rank(B, I, O),
	numLinks(B, C).

numLinks(A, 1) :-
	edge(A,B).

numPages(A, 1) :-
	edge(B,A).