# [EM] RCV Challenge

Forest Simmons forest.simmons21 at gmail.com
Sun Dec 26 16:59:28 PST 2021

```Kevin,

Simplest River formulation ever! I think that's my new favorite.

And thanks for keeping all of these valuable insights alive ... very
stimulating!

And yes, IACC is just another formulation of TACC.

In that regard I wonder if it would be better to use the implicit approval
winner's recommended/published order  rather than the implicit approval
order itself. It seems like that would strongly discourage the likely IA
winner from burying the sincere CW.

El dom., 26 de dic. de 2021 1:17 p. m., Kevin Venzke <stepjak at yahoo.fr>
escribió:

> Hi Forest,
>
> Does IACC give different results from TACC? Off the top of my head it
> seems that
> in a three-candidate cycle both methods will elect whichever candidate
> beats the
> approval loser.
>
> For myself, here's a short list of ideas.
>
> 1. As you initially described this challenge (with UD, monotonicity, clone
> independence) the bar seemed very high, making me think only a few methods
> would
> be worth mentioning.
>
> One of them is River. If I'm not mistaken River's resolution process can be
> explained and executed very easily.
>
> Say that each candidate "has" a set of candidates, which initially
> contains only
> the candidate himself.
>
> Evaluate the propositions from strongest to weakest.
>
> When you consider "A beats B," ask simply whether B is still in his
> original
> set. If so, then move every candidate in B's set into whichever set A
> currently
> occupies. Otherwise do nothing.
>
> (If A is in B's original set, it's the same result to move or to not move.)
>
> After considering all the propositions, elect from among the candidates who
> remain in their original set.
>
> If I deviate from the criteria:
>
> 2. Condorcet//Approval with implicit approval is probably the simplest
> Condorcet
> method that I like. I think with three slots it's best, though. It's very
> simple
> to understand, and burial strategy has high risk.
>
> 3. I am still intrigued by the "BTP" method from a year ago, in which
> voters
> basically acquiesce to every candidate who "Beats or Ties" each candidate
> "Preferred" to them on that ballot. I'm still unsure what pitfalls this
> method
> may have.
>
> It is a strange quirk to see, for example, Gore prevail over Bush with
> acquiescence interpreted to come not from the Nader voters, but from the
> Bush
> voters.
>
> 4. Not quite a Condorcet method, but I like Approval-Elimination Runoff in
> which
> we eliminate the least-approved candidates until there is a majority
> favorite.
>
> 5. My "King of the Hill" method. Between the first preference winner and
> the
> candidate with the most first preferences who is involved in a
> majority-strength
> pairwise contest with the FP winner, elect the winner of that contest, if
> there is
> such a contest.
>
> This is based on the intuition that a high first preference count indicates
> viability, and that respecting a full majority among such candidates
> should at
> least ensure the winner comes from the "correct" side of the spectrum. This
> method also admits no burial strategy.
>
> Kevin
>
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