[EM] Approval-enhanced IRV (take 2)

[C.Benham]

Forest,

I'm glad you approve.

> So if a voter was giving out too much approval by approving below one 
> of the mandatory semi-finalists, the method fixes that faux pas for free!
>

Also the voter might not be making the innocent "mistake" of risking the 
IRV winner being defeated in the final by a candidate they like less, but
could be trying a relatively easy and tempting Push-over strategy.

Chris

On 23/08/2023 8:54 am, Forest Simmons wrote:
>
>
> On Mon, Aug 21, 2023, 9:36 AM C.Benham <cbenham at adam.com.au> wrote:
>
>
>     This is I think more appealing and streamlined than my earlier
>     version.
>
>     *Voter strictly rank from the top however many candidates they wish.
>
>     Also they can mark one candidate as the highest ranked candidate they
>     approve.
>
>     Default approval is only for the top-ranked candidate.
>
>     Determine the IRV winner.
>
>     On ballots that approve the IRV winner, approval for any candidate or
>     candidates
>     ranked below the IRV winner is withdrawn.
>
>     Elect the pairwise winner between the (thus modified) approval winner
>     and the IRV
>     winner.*
>
>
> So if a voter was giving out too much approval by approving below one 
> of the mandatory semi-finalists, the method fixes that faux pas for free!
>
> What if the approval cutoff were simply moved adjacent to the IRV winner?
>
> That would probably give the IRV winner's strongest defeater too much 
> help, and wrest too much control of the approval lever from the 
> sovereign voters.
>
>  It looks like you are treating the malady with the minimal effective 
> dose of the right medicine!
>
> Great!
>
> Who will spread the good news?
>
>
>     This works fine in the same way as the earlier version in the example
>     given to talk
>     about Minimal Defense and Chicken Dilemma.
>
>     It is more Condorcet efficient than normal IRV, and meets (or comes
>     close enough
>     to meeting) appropriately modified versions of the LNHs and
>     Minimal Defense
>     and Chicken Dilemma.
>
>     49 A  (sincere might be A>B)
>     24 B   (sincere might be B>C)
>     27 C>B
>
>     If the C voters B>A preference is strong they can by approving B
>     avoid
>     regret for not Compromising.
>
>     Then the final pairwise comparison will be between B and A and B
>     will win.
>
>     But if they are more concerned about not letting the B voters
>     steal the
>     election from them by possible Defection strategy then they can do
>     that by not
>     approving B.
>
>     49 A>C>>B
>     48 B>>C>A
>     03 C>A>>B
>
>     Say this is for a seat in Parliament, and the voters have been
>     accustomed to using FPP,
>     IRV or Top-Two Runoff. It would cross the mind of no-one that the
>     "Condorcet winner"
>     C should defeat the IRV (and FPP and even Approval) winner A.
>
>     But according to Condorcet advocates the B voters should or could be
>     regretting no getting an outcome they somewhat prefer by all top
>     voting C.
>
>     Well with this system the B and C voters together can "fix" this
>     without
>     anyone betraying their favourites or reversing any sincere
>     preferences simply by all of
>     them approving C and not A.  Then the final pairwise comparison
>     will be between C and A
>     with C winning.
>
>     Chris Benham
>
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