[EM] CD & truncation-resistance. Definitions people like.

[C.Benham]

On 10/12/2016 12:12 PM, Michael Ossipoff wrote:

> Regarding the CD example, Chris suggested scenarios in which one of 
> the other candidates, not A, is the CWs.

33: A>B
32: B (sincere may be B>A)
34: C


Mike,

I don't recall doing that exactly.   I like compliance with CD. The 
example I posted recently:

> Given that burial vulnerability is unavoidable in Condorcet methods, I 
> think that is more democratic if  (in this respect) larger factions
> have the advantage over smaller factions.
>
> 43: A
> 03: A>B
> 44: B>C  (sincere is B or B>A)
> 10: C
>
> C>A  54-46,    A>B  46-44,   B>C 47-10.
>
> Here A is the sincere CW and supported by the largest of the three 
> factions of voters, but Winning Votes rewards the buriers by electing B.
>
> Benham and  LV(erw)SME   easily elect  A.    Smith//Approval elects C.

The  "WV strategy" enthusiast might chastise the 3 A>B voters for 
allowing the B supporters' burial to succeed by not truncating but if 
they'd
done that then WV would have elected their least-preferred candidate.

The tops-of-the-ballots oriented Benham and  LV(erw)SME  handle the 
scenario by (effectively) laughing off C (and electing A in breach of
Minimal Defense), while the more bottoms-of-the-ballots oriented 
Smith//Approval notes that C is the most "approved" (i.e. voted above
bottom) candidate and says to the 44 B>C voters "since you voted for C 
you can have C".

> Chris recently mentioned an incompatibility between CD & Minimal 
> Defense (Eppley's votes-only version of SDSC or WDSC).

C: Certainly we can't have all three of  Plurality, CD and Minimal Defense.

> When discussing Margins Sorted Approval, I objected that it penalizes 
> truncation instead of electing the CWs

C: MSA isn't one of my very favourite Condorcet methods, but I prefer it 
to Winning Votes.  In the example it elects C.

Chris Benham


> Regarding the CD example, Chris suggested scenarios in which one of 
> the other candidates, not A, is the CWs.
>
> What if B is CWs?
>
> Then we have a truncation example, in which the C voters are truncating B.
>
> For C to win would be a violation of truncation resistance. ...if B is 
> CWs & this is a truncation example.
>
> But no problem: MMPO elects A instead of C.
>
> Chris recently mentioned an incompatibility between CD & Minimal 
> Defense (Eppley's votes-only version of SDSC or WDSC).
>
> Maybe the truncation resistance failure of electing C is related to 
> that incompatibility.
>
> Electing A avoids the problem.
>
> When discussing Margins Sorted Approval, I objected that it penalizes 
> truncation instead of electing the CWs. But that isn't really a problem:
>
> If your truncation is principled, then you have no reason to object 
> when the CWs thai you don't like doesn't win.
>
> ..nor does anyone have a complaint.
>
> If your truncation is careless, then just be more careful
>
> If your truncation is hurried, then allow yourself more time.
>
> So the election of A isn't a problem if B is CWs & it's a truncation 
> example.
>
> Plurality Criterion? Of the candidates other than the most 
> pairwise-opposed one, A is the most favorite.
>
> There's no important objection to electing A if B is CWs.
>
> What if C is the CWs, & the A voters are burying C?
>
> C would be a peculiar CWs, unsupported from both sides. No support 
> other than hir 1st choice voters.
>
> There's surely no important objection if such an unsupported candidate 
> doesn't win.
>
> So, no matter how you look at it, there's no objection to electing A 
> in the CD example.
> --------------------
> I told of how someone didn't accept ICT because of its relatively 
> wordy & unfamiliar definition.
>
> When offered list of methods, that person chose Approval as favorite.
>
> Hearing the MMPO definition, she didn't consider it un-intuitive, 
> complicated, overly wordy or without obvious justification.
>
> It elects someone least unpreferred to someone else.
>
> What could be more simple, obvious & natural?
>
> She didn't object to MMPO as she objected to ICS
>
> Yes there are strongly-felt objections to MMPO. I've answered them.
>
> Yes MMPO shares wv's possibility of perpetual burial fiasco, but it 
> may well never happen. It doesn't keep wv from being one of the most 
> popular methods.
>
> FBC, Weak CD, wv strategy. A lot of important advantages.
>
> Wv strategy means that the CWs is better & more easily protected than 
> in any other rank-methods.
>
> Michael Ossipoff
>
>
>
> ----
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