[EM] What are some simple methods that accomplish the following conditions?

[Forest Simmons]

A simple, easy to understand solution!

On Wed, Jun 26, 2019 at 10:10 PM C.Benham <cbenham at adam.com.au> wrote:

> Earlier in response to this I suggested some Condorcet methods. Here is a
> non-Condorcet method
> that also fills the bill: a tweaked IRV:
>
> *Voters strictly rank  candidates from the top and also give an approval
> cutoff, default placement
> of which is just below top.
> Candidates that are pairwise beaten by a more approved candidate are
> disqualified.
> If more than one candidate is undisqalified then eliminate the candidate
> highest-ranked on the fewest
> ballots. Repeat until only one undisqualified candidate remains. Elect
> that candidate.*
>
> As compensation for failing Condorcet, this should keep most of IRV's
> resistance to Burial strategy and
> be more-or-less immune to the "DH3" pathology.  The normal IRV winner can
> only lose to a candidate
> that both pairwise beats it and is explicitly more approved.
>
> https://rangevoting.org/DH3.html
>
> In all 3 of Forest's scenarios all but one candidate is disqualified.
>
> Chris Benham
>
> On 31/05/2019 8:03 am, Forest Simmons wrote:
>
> In the example profiles below 100 = P+Q+R, and  50>P>Q>R>0.
> I am interested in simple methods that always ...
>
> (1) elect candidate A given the following profile:
>
> P: A
> Q: B>>C
> R: C,
> and
>
> (2) elect candidate C given
> P: A
> Q: B>C>>
> R: C,
> and
>
> (3) elect candidate B given
> P: A
> Q: B>>C  (or B>C)
> R: C>>B. (or C>B)
>
> I have two such methods in mind, and I'll tell you one of them below, but
> I don't want to prejudice your creative efforts with too many ideas.
>
> Here's the rationale for the requirements:
>
> Condition (1) is needed so that when the sincere preferences are
> P: A
> Q: B>C
> R: C>B,
> the B faction (by merely disapproving C without truncation) can defend
> itself against a "chicken" attack (truncation of B) from the C faction.
>
> Condition (3) is needed so that when the C faction realizes that the game
> of Chicken is not going to work for them, the sincere CW is elected.
>
> Condition (2) is needed so that when  sincere preferences are
> P: A>C
> Q: B>C
> R: C>A,
> then the C faction (by proactively truncating A) can defend the CW against
> the A faction's potential truncation attack.
>
> Like I said, I have a couple of fairly simple methods in mind. The most
> obvious one is Smith\\Approval where the voters have control over their own
> approval cutoffs (as opposed to implicit approval) with default approval as
> top rank only.The other method I have in mind is not quite as simple, but
> it has the added advantage of satisfying the FBC, while almost always
> electing from Smith.
>
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