[EM] IRV in San Francisco

Paul Kislanko kislanko at airmail.net
Tue Nov 16 14:03:31 PST 2004

Eric Gorr replied to my questions: 
> At 3:14 PM -0600 11/16/04, Paul Kislanko wrote:
> >No one can be added or removed
> >from a ballot after the votes have been counted,
> Sure one can...just do it and recalculate.
> >so by this distinction
> >there is no such thing as an IIA spoiler.
> I believe there is.
> Compute the winner.
> Start removing candidates and see if you can get the winner to change.
> If the winner changes, you have a spoiler via IIA.
That's what I said below - this is an analytical tool to determine how a
method works logically.

> >ICC is just a weaker version of IIA, and has to be weaker 
> because nothing
> >can pass IIA and meet three other desirable criteria.
> What ICC and IIA are you using?
Whichever ones you are. It wasn't ME that claimed that the difference was in
ICC the candidates were already on the ballot, but to be precise we note
that in your reply you said that in IIA they were on the ballot and you just
remove them and add them back in. 

That's why I said the distinction is confusing. Now you say there is no
distinction. So I'm still confused.

> On what basis do you call the ICC a weaker version of IIA?
> Does your statement imply that if a method passes Dr. Arrow's IIA, it 
> must pass Dr. Tidemans ICC?

I make no such claim, but Dr. Arrow proved that no method could meet IIA and
the other three of his "reasonable" criteria. If ICC is related to IIA and a
method can meet Arrow's other three and also meet ICC, then per force ICC
must be a weaker criterion than IIA, else there would be a flaw in Arrow's

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