In the following program, i want to compute the paths: <code> rule "base" when edge : Edge(x : first, y : second) not Path(first == x, second == y) then insert(new Path(edge.getFirst(), edge.getSecond())); end rule "recursive" when edge : Edge(x : first, z : second) path : Path(first == z, y : second) not Path(first == x, second == y) then insert(new Path(edge.getFirst(), path.getSecond())); end </code> My question: How to express the query "path(cityA, X)?" efficiently in drools? Since the first element is bound to 'cityA', I am wondering whether drools can make use of it. I think there should be more efficient way than firing all rules. Thanks, Senlin Liang