[EM] Re: ICC and Approval
James_Green-Armytage at antioch-college.edu
Mon Jun 13 19:35:22 PDT 2005
James replying to Mike, on the subject of ICC definitions...
>So, ICC definition is changed to this, for use in evaluating non-ranked
>I trust that you meant "in evaluating both rank and non-rank methods".
>kind of ICC that you describe applies meaningfully and usefully to rank
>methods and non-rank methods. To all methods.
>I trust that you wouldn't use different ICC definitions, one for rank
>methods and one for non-rank methods.
Yes, but if we apply the universally applicable (preference) version of a
criterion to rank methods (that allow equal ranking), it becomes
equivalent to the corresponding votes only criterion, and hence the extra
verbiage is unnecessary.
>Set S is a clone set if, for every particular voter, and for any
>outside S, if that voter prefers somone in S to X than s/he prefers
>everyone in S to X; and if that voter prefers X to someone in S, then
>prefers X to everyone in S; and if that voter is indifferent between X
>some candidate in S, then s/he is indifferent between X and every
>A voter is indifferent between X and Y if s/he doesn't prefer X to Y and
>doesn't prefer Y to X.
>[end of clone-set definition]
Sounds good to me.
>You left out the stipulation about how preference constrains voting. The
>usual one for ICC is that everyone votes sincerely.
> I have proposed a modified version of ICC such that candidates must be
>given identical cardinal/approval scores by all voters to qualify as
>clones, in addition to the standard qualification rule. I believe that
>approval and cardinal pairwise both pass this modified version of ICC, but
>not the standard ranked ballot version.
>No criterion should have a special ranked-ballot version. The ICC that
>described, or my improved wording of it, is ICC for all methods.
Yes. For that reason, the criterion I suggest should be considered to be
a separate criterion from traditional ICC.
>By your alternative clone-set definition, there can be no such thing as a
>clone-set with more than one candidate when the method is Plurality, or
>the method is Borda or IRV, as those latter two are usually propoed.
I should clarify my proposed criterion by saying that the additional
requirement only applies if the method has a cardinal ballot. In that
case, plurality and Borda continue to fail, while IRV continues to pass.
>One could write a preference clone set definition that says that S is a
>clone set if everyone is indifferent between S's members. Pluralty,
>and IRV would fail the resulting criterion, meaningfully. But you
>call it a clone set, because that name is already taken. How about
Okay, but are you sure that IRV fails?
More information about the Election-Methods