Why do you need to break ties? Wouldn't it make more sense to consider ties to be ranked equally?
If you are trying to do it in as few ballots as possible, you might also consider leaving tied candidates in their previous relative sort position (from the last time through the loop). The problem I see is that using borda scores is just rather arbitrary, but worse, randomly breaking ties is non-deterministic. In any case this is a fascinating exercise and I could see it being useful. I would be very interested to see it applied to a real IRV election....see how different the results are if you first "compress" it into a pairwise matrix then reexpand (deconstruct) it into ballots and tabulate it again. -rob ---- election-methods mailing list - see http://electorama.com/em for list info
