[EM] TACC (total approval chain climbing) example

[Michael Ossipoff]

On Sat, Apr 19, 2014 at 7:28 PM, Forest Simmons <fsimmons at pcc.edu> wrote:

> Let's consider the following ballot set:
>
> 48 C
> 27 A>B
> 25 B
>
> Plurality says that A cannot win, because C has more top votes than A is
> ranked.
>
> The Chicken Dilemma Criterion says that B cannot win, because there is a
> possibility that the B faction is defecting from a true preference of B>A.
>
> That leaves C as the only acceptable winner for this ballot set.
>
> How do various methods stack up on this ballot set?
>
> MinMaxPairwiseOpposition (MMPO) elects A.
>
>
What I finally decided that I didn't like about MMPO was its bottom-end
strategy. But I also realized that its Plurality failure could make
embarrassing bad-examples, like the one that Kevin posted, which could be a
criticism-vulnerability.



> Condorcet(wv) and Condorcet(margins) both elect B.
>
> Implicit Approval elects B.
>
> Borda, TACC, and IRV based methods like Woodall and Benham elect C.
>
> But Borda is clone dependent, and the IRV style elimination based methods
> fail monotonicity.  So TACC is a leading contender if we really take the
> Chicken Dilemma seriously.
>

Yes, TACC definitely qualifies as a contender, along with Benham and
Woodall, and,to a lesser extent, IRV, which isn't quite quite as good, due
to its Condocet-Criterion failure.
.

>
> But what if the ballot set is sincere?
>
> In that case it seems like B should be the winner.
>
> The problem is that standard election methods have no way of detecting
> ballot sincerity.
>
> Therefore there is no strategy free method for covering both scenarios.
>
>
For Green-scenario conditions, where there can be chicken-dilemma (but FBC
isn't necessary, due to honest media and non-gulllible electorate), I
suggest Benham, Woodall, and TACC.

For ideal majoritarian conditions (no chicken dllemma or FBC-need), I
suggest MAM as the best choice.

Polls, such as those at Condorcet Internet Voting Service (CIVS), at:

http://www.cs.cornell.edu/andru/civs.html

...seem to be free of strategic voting. That's ideal majoritarian
conditions, and so, for that, I suggest MAM.

MAM is one of the rank-count-methods offered at CIVS.

CIVS has a number of polls regarding political parties, and categories of
political partes.  Additionally there's a candidate poll that was set up
for te 2012 election, but which might still be taking votes too.

I feel that, in official public elections, the chicken dilemma would
devastate the progressives. All of the progressve parties agree to a
remarkable degree, regarding the material justice and life-quality
improvements for ordinary people. But they don't always speak so well of
eachother.

Sure, I've long advocated Approval for current conditions, because current
conditions require FBC, and because Approval is a minimal change in
Plurality. And in that advocacy, I've said that the chicken-dilemma can be
dealt with. Yes it can, but it can require electing a Republocrat, just to
teach a defecting progressive faction a lesson. No one wants to have to
deal with that if it can be avoided.

Without FBC-need, it's possible to get MMC, CD and Condorcet in one method
(Benham or Woodall). Of course an advantage of TACC is that it meets those
criteria, plus Monotonicity.

(I realize that those methods' Smith compliance confers MMC and Condorcet
compliance)

As you mentioned, in the Smith + CD complying methods we've discussed, a
little Approval-like voting by A voters can protect B, in your example,
when the B voters are felt to be sincere, not defecting.

Michael Ossipoff








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