The problem with this approach is it can't preserve the unknown status of the orderings, to be resolved by later orderings. In the first example, "S Y A" and "S N A" should combine in a way that expresses a very low preference for Y coming before N, and then that low preference should get overridden by the strong preference for Y coming before N by the 3rd rule. (and it would have made a better example if I put N before Y in the 3rd rule because then the strong preference would be contrary to the default order)