[EM] Withdrawals

Wed Nov 16 06:21:06 PST 2016

In PAR, withdrawing makes sense in the many of the same cases where
favorite betrayal does. For instance:

   - 30: AX>B
   - 5: AX>C (accepting C may be purely strategic, or honest; we don't know)
   - 15: B>A
   - 10: B>AC
   - 29: C>B
   - 11: CB

C is initially considered the "frontrunner", but cannot hold that lead
against A; then A wins as the least-rejected. But if C were rejected, B
would the initial frontrunner, then that lead would hold and B would win;
since C's top-voters universally prefer that result over A winning,
presumably C would want to withdraw.

This is the same situation where, in FBPPAR, C's top-voters would be
strategically advised to mark C as "stand aside".

Note that, unlike the cases Juho pointed out, this does not break down in
the case of a Condorcet cycle. "Withdraw" would not mean "don't let me
win", it would just mean "never consider me as leader"; so in a CC, all
candidates would rationally withdraw, and PAL would simply devolve to
approval using all above-bottom votes. (Note that this is the rational
equilibrium vote in approval for all the pro-cyclical voters, by definition
a majority, and the locally-optimal-though-not-equilibrium vote for a
substantial fraction of the anti-cyclical voters.)

I think that withdrawal is easier to explain than FBPPAR, so I think
PAR-with-withdrawal is a good option if you want a system that's even
closer to FBC than PAR.

2016-11-16 5:11 GMT-05:00 Juho Laatu <juho.laatu at gmail.com>:

> Hi guys. I have not read the whole stream but I throw in some words on
> withdrawals anyway.
>
> One must accept that the winner can withdraw since it is always possible
> that the winner becomes sick and we can do nothing about that. It is
> impossible to tell if he is withdrawing for this kind of reasons or for
> some other less acceptable reasons (e.g. if some of the competitors pays
> him money to withdraw, or if he took part in the election just for fun to
> show that he can beat the others).
>
> Allowing others to withdraw is more problematic. Let's say there's a
> Condorcet cycle A>B>C>A (in some Condorcet method), and one of the
> candidates (B) can change the winner (A) by withdrawing from the race. This
> would make it possible for him to sell the victory to one of the
> competitors (C in this example) of the (original, quite likely sincere)
> winner. That is probably not what we want.
>
> In Condorcet methods it is possible that many of the B voters would like
> the idea of changing the winner from A to C (they may have voted B>C>A).
> But probably not all. If we allow withdrawals, and they are commonly used,
> maybe (in a three candidate cycle A>B>C>A) the method should declare B the
> original winner instead of A, since that would make it possible for C to
> withdraw, and A would win (the candidate that should have won in our
> opinion in the first place). That doesn't sound good. Maybe it is better to
> use the election method to pick the best winner, and not allow the
> candidates to agree after the election who the winner is.
>
> I note that we could allow any of the candidates to "withdraw
> conditionally if they win". In that case the withdrawal of a non-winning
> candidate would never change the winner. The votes would stay the same even
> after this kind of withdrawals. This would however allow the U.S.
> presidential election style withdrawals where the other candidate (or all
> the other candidates?) can withdraw when they are sure that they have no
> chances to win. This kind of withdrawal could change the winner only in the
> case that a recount would make the withdrawing candidate the winner. And in
> this case we would back in the scenario where the winner is in any case
> allowed to withdraw.
>
> Some methods might benefit of the possibility of allowing a candidate to
> withdraw in order to allow a clone candidate to win. If the method has this
> kind of serious problems with clone nomination, it might be better to use
> some candidate declared strategy instead of allowing individual candidates
> to change the result by allowing them to strategically withdraw. A simple
> declared strategy (in some methods) could be to allow those candidates to
> declare themselves as clones _before_ the election. In the cyclic ranked
> example (A>B>C>A), B and C could be candidates of the same party, and it
> would make sense to allow one of them to win, if party "BC" has majority.
> Even if A would be the best winner with sincere votes, we may agree that B
> (or maybe C) is the best winner (with about 66% majority). We probably had
> quite a few C>A>B voters that would want A to win instead of B. But they
> knew already when they voted for C that B would inherit those votes. Fair
> deal, no betrayal, nor strategic plotting after the election.
>
> (An extreme method with this kind of declared candidate strategy would be
> one where the candidates are organized as a complete binary tree. It would
> not make sense to rank the candidates. Bullet voting would be sufficient
> since the inheritance route of all the votes would be fixed anyway.)
>
> BR, Juho
>
>
>
> On 16 Nov 2016, at 03:21, Michael Ossipoff <email9648742 at gmail.com> wrote:
>
> Yes, if it's freely negotiated by the candidates, then there wouldn't be
> that vulnerability to strategic voters.
>
> Michael Ossipoff
>
> On Tue, Nov 15, 2016 at 7:39 PM, Forest Simmons <fsimmons at pcc.edu> wrote:
>
>> It's not really clear to me; it seems like it depends on the dynamics of
>> the candidate withdrawals when no candidate is forced to withdraw until
>> they think it is safe to do so.  There might be some bluffing and
>> standoffs, so it would depend on the negotiation skills of the candidates.
>> Especially if they are allowed to decide on the fly whom to transfer the
>> unspecified choices to.
>>
>> On Tue, Nov 15, 2016 at 2:58 PM, Michael Ossipoff <email9648742 at gmail.com
>> > wrote:
>>
>>> But, if that will elect the CWs, with sincere voting, then isn't there
>>> still an incentive and vulnerability for some faction to falsify
>>> preferences to make a strategic cycle that they might win, if they don't
>>> like the likely CWs?
>>>
>>> Michael Ossipoff
>>>
>>> On Tue, Nov 15, 2016 at 3:10 PM, Forest Simmons <fsimmons at pcc.edu>
>>> wrote:
>>>
>>>> Combining Candidate Withdrawal with Candidate Transfer:
>>>>
>>>> When a candidate withdraws, hir votes are distributed in accordance
>>>> with the additional preferences of hir supporters.  When no additional
>>>> preferences are specified, it is assumed that the voter supports the
>>>> preference order of the withdrawing candidate.
>>>>
>>>> Voters may place NOTB (none of the below) above their truncated
>>>> candidates.  If at any stage the NOTB candidate accumulates more than
>>>> two-thirds (say) of the votes, the election is scuttled and new candidates
>>>> must be nominated.
>>>>
>>>> On Mon, Nov 14, 2016 at 9:55 PM, Michael Ossipoff <
>>>> email9648742 at gmail.com> wrote:
>>>>
>>>>> But, even if that rule were extended to rescue a CWv that's farther
>>>>> down in the rankings  I guess that would just be like having a rule to
>>>>> elect the CWv if there is one, and otherwise to do IRV, which would be a
>>>>> less-good relative of Benham & Woodall.
>>>>>
>>>>> And of course a rule to elect  the CWv is always vulnerable to
>>>>> strategic falsification of preferences to make a strategic cycle, with the
>>>>> problems that go with that.
>>>>>
>>>>> In fact, I guess that the candidate-withdrawal option, Steve Eppley's
>>>>> original proposal, would, as well, be vulnerable to a faction making a
>>>>> strategic cycle, to avoid a result in which the election of the CWv is
>>>>> inevitable due to the candidate-withdrawal that will happen if ordinary IRV
>>>>> doesn't elect the CWv..
>>>>>
>>>>> Oh well, so much for that possibility :^)
>>>>>
>>>>> Michael Ossipoff
>>>>>
>>>>> On Mon, Nov 14, 2016 at 10:47 PM, Michael Ossipoff <
>>>>> email9648742 at gmail.com> wrote:
>>>>>
>>>>>> Speaking of candidate-participation methods, Steve Eppley proposed
>>>>>> the simplest one: the Candidate Withdrawal option.
>>>>>>
>>>>>> When the count result is announced, any candidate has 24 hours in
>>>>>> which to announce hir withdrawal from the election, and call for a re-count
>>>>>> with hir deleted from the ballots.
>>>>>>
>>>>>> An IRVist objected to that, because withdrawal betrays the
>>>>>> candidate's voters.  Ok, then add a rule that a winning candidate can't
>>>>>> withdraw :^)
>>>>>>
>>>>>> The candidate withdrawal option would completely save IRV from its
>>>>>> problem. Candidate-withdrawal should be offered as an amendment to IRV
>>>>>> proposals, and also to already-enacted IRV.
>>>>>>
>>>>>> But, just looking at IRV, the circumstances for wanting to withdraw
>>>>>> (Your voters let the CWv get eliminated, by ranking hir 2nd instead of 1st,
>>>>>> and hir votes transferred the other way) seem so well-defined and specific
>>>>>> as to suggested an automated candidate-withdrawal, built into the IRV
>>>>>> count-rule.
>>>>>>
>>>>>> How about saying that, when that happens, the count rule will delete
>>>>>> the 1st choice that is in the way of the eliminated CWv being at the top of
>>>>>> the rankings that didn't help CWv because they ranked hir 2nd, and their
>>>>>> vote never got to hir?   ...followed by a 2nd count without the deleted 1st
>>>>>> choice?
>>>>>>
>>>>>> ...or it could be an option for the voter to choose if s/he wants
>>>>>> that deletion and re-count to occur if hir 1st choice eliminates a CWv,
>>>>>> resulting the election of someone over whom you ranked the CWv.   ...where,
>>>>>> without that 1st choice, the CWv would have won.
>>>>>>
>>>>>> That option would only apply to the first election result, and not to
>>>>>> subsequent ones.
>>>>>>
>>>>>> The method could be called "Automatic Strategic Dropping"
>>>>>>
>>>>>> Or, IRV with that option could be called "Auto-Revotable IRV".
>>>>>>
>>>>>> I don't like the name IRV. Its meaning isn't a good description. RCV
>>>>>> is even worse, because _every_ rank-balloting method is RCV.
>>>>>>
>>>>>> I'd like to rename IRV as "Delete Least Favorite", "Delete Least
>>>>>> Top", "Eliminate Least Favorite" or "Eliminate Least Top".
>>>>>>
>>>>>> That would be DLF, DLT, ELF, or ELT.  How about ELF?
>>>>>>
>>>>>> That name goes with my brief definition of the IRV count:
>>>>>>
>>>>>> Repeatedly, delete from the rankings the candidate currently topping
>>>>>> fewest rankings.
>>>>>>
>>>>>> [end of definition of ELF definition]
>>>>>>
>>>>>> If that action is repeated, it will eventually leave only one
>>>>>> un-deleted candidate.
>>>>>>
>>>>>> So "Auto-Revotable Eliminate Least Favorite"?
>>>>>>
>>>>>> Michael Ossipoff
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Nov 14, 2016 at 6:57 PM, Forest Simmons <fsimmons at pcc.edu>
>>>>>> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Sat, Nov 12, 2016 at 9:29 PM, Michael Ossipoff <
>>>>>>> email9648742 at gmail.com> wrote:
>>>>>>>
>>>>>>>> Yes, it would make sense, and be interesting for a voting-system
>>>>>>>> reform proposal to include CVT in its list of offered methods. Offer a
>>>>>>>> complete variety, and let the initiative committee &/or the public choose.
>>>>>>>> The addition of CVT would greatly broaden the variety. So the list could be:
>>>>>>>>
>>>>>>>> Approval
>>>>>>>> Score
>>>>>>>> Bucklin
>>>>>>>> MDDTR
>>>>>>>> CVT
>>>>>>>>
>>>>>>>> Actually, it might be best to include IRV, with a fair assessment
>>>>>>>> of its advantages & disadvantages, so that people won't think that IRV is
>>>>>>>> being prejudcially ignored, and so as to answer, in advance, any arguments
>>>>>>>> from FairVote.
>>>>>>>>
>>>>>>>> Michael Ossipoff
>>>>>>>>
>>>>>>>> I agree, IRV should be included for the reasons you suggest.
>>>>>>>
>>>>>>> Also, I think that the inclusion of a NOTA (none of the above)
>>>>>>> option on the ballot should be a part of the CTV suggestion:  If NOTA gets
>>>>>>> the highest total it means that too few of the voters trust the competence
>>>>>>> and integrity of their favorites to act as proxies for them.
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
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