12. The method of claim 10 , wherein the calculating of the ranking values for the two or more contributors is an iterative process comprising repeated calculation of interim ranking values for the two or more contributors.
12. The method of claim 10 , wherein the calculating of the ranking values for the two or more contributors is an iterative process comprising repeated calculation of interim ranking values for the two or more contributors. 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.