[EM] How to describe RAV/ARC

Forest Simmons simmonfo at up.edu
Tue Mar 15 14:12:08 PST 2005


On Tue, 15 Mar 2005, Ted Stern wrote:

> I don't think
> anybody could argue with that.


Bart inoculated me against ever using that sentence :')

Here's my sales pitch (to EM members) for RAV/ARC:

When candidate X beats Y in both approval and by head-to-head choice, 
let's say that X strongly beats Y.

If X strongly beats Y then both approval and pairwise methods agree that Y 
should not win.

What happens if we eliminate all of the candidates that are strongly 
beaten?

The remaining candidates form a set P that are totally ordered by the 
ordinary pairwise beat relation.

The top of this totally ordered chain is the RAV/ARC winner.

That ends my EM sales pitch for RAV/ARC. [I would use a different pitch 
for the general public.]

But now let me continue on to a sales pitch for a related method:

We got the set P by eliminating all of the candidates that both Approval 
and Condorcet agree should be eliminated.

The remaining candidates are the subjects of irreconcilable disagreement:

As we noted above, they are totally ordered by by the ordinary pairwise 
beat relation, but I forgot to mention that they are also totally ordered 
by approval order.

That would be fine except that these two orders are diametrically opposed; 
one is the exact reverse of the other.

In other words the set P is the set of candidates on which approval and 
Condorcet have irreconcilable disagreement.

Any unbiased compromise between Approval and Condorcet must give each 
member of P a chance of winning.

Random ballot from P results in a fair chance that is monotonic and clone 
proof.


Forest



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