[EM] MMPO

[Janet Robinson]

I should define MMPO. It was probably introduced by Kevin  Venzke, but I'm probably its only advocate. More about that later in this posting.

MMPO:

Rank as many candidates as you want to. Equal ranking allowed.

The winner is the candidate with fewest people ranking the same candidate over hir.

(end of dfn)

Why most EM participants don't like MMPO:

Participation Criterion failure: I answered that objection a day or two ago

Kevin posted an example of MMPO giving a result that didn't look or feel right.   ...a result that, in fact, could be called ridiculous.yyy

Welcome to rank-methods!

Say an election is being conducted by MAM, Beatpath, IRV, or MJ:

You show up, & cast a ballot on which you rank or rate X over Y. Your ballot changes the winner from X to Y.

Dare I say that's ridiculous?

In fact, it's worse than ridiculous, because it uses your ballot to do something opposite to your voted wishes.

MJ can do that even jf X & Y are the only candidates you vote for.

Kevin's example doesn't show MMPO acting opposite to a voter's expressed wishes.

In fact, it was shown that no one really would have a valid complaint about the example's result.  (The voter whose voted preference is oppositely responded to, in my scenario above, _does_ have a valid complaint.)

In other words, MMPO's ridiculous result is less bad than one that is common  in rank methods.

Look, if you if you don't want it to be possible to contrive an example in which the voting-system will do something ridiculous (even if strategicaly harmless & not object-able), then you need to stick with Approval or Score.

MMPO offers an entirety, dramatically, unequalled combination of important strategic properties:

CD (no chicken dilemma)

FBC (option of fully-effectjve approval voting)

Its non-chicken-dilemma strategy is like MAM's maximally unproblematic strategy.

It effectively meets MMC.

Opponents will exploit the objections?

Tell about them in your proposal. Tell the answers to them. Tell of MMPO's remarkable, unique property-set.

Let the voters &/or the proposals committee decide for themselves.

Michael Ossipoff


On September 11, 2016, at 5:07 PM, Janet Robinson <email9648742 at gmail.com> wrote:

Is there a method that meets  CD, and is otherwise as good as Bucklin or MAM?

I'm aware of only one: MMPO.

Meets CD, and otherwise its strategy is like that of MAM.

The only CD method that makes a good unlimited-rankings method.

Embarrassment examples? Sure. Those have no practical importance.

The Plurality Criterion says, in the standard CD example, that A shouldn't win.

Who should?

C? C is the only majority-beaten candidate.

B, because the A voters ranked hir? This isn't Borda, Score or Approval. The A people ranked B over C to defeat C, not to make B beat A.

If the Plurality Criterion says A shouldn't win, the Plurality Criterion is mistaken.

I still consider the CD Approval methods the best. Especially 3-Slot ICT.

But MMPO is the best unlimited rankings method. 

Bottom-end strategy? Sure, like that of MAM and  Beatpath.

MAM & Bucklin are good too.

Michael Ossipoff