13. The method of claim 12 , wherein the iterative process comprises calculating the interim ranking values in a sequence determined at least in part by respective initial ranking values, with lower initial ranking values being earlier in the sequence.
13. The method of claim 12 , wherein the iterative process comprises calculating the interim ranking values in a sequence determined at least in part by respective initial ranking values, with lower initial ranking values being earlier in the sequence. 14. The method of claim 13 , wherein, after a first iteration of the iterative process, the initial ranking values comprise the interim ranking values produced by an immediately preceding iteration of the iterative process.