[EM] My CTE post to EM

[C.Benham]

Michael,

> ... there's no offensive strategy for changing the winner from the CW
> to one's own favorite,

Say sincere is

46 A
44 B
10 C

A is the CW (as well as being every other type of winner).

Now suppose the B voters all decide to bury against A by ranking C second:

46 A
44 B>C
10 C

Now  C has the lowest Borda score and the lowest "top count", so if we 
are using
IRV/RCV or Baldwin  C is eliminated, "taking down" A and leaving B elected.

The "offensive strategy" has succeeded. This is the same outrageous 
failure of
the Later-no-Help and Plurality criteria that we see with Margins.

I'm not clear how Coombs (or your preferred version of it) handles 
truncation.

Is the "bottom count" Fractional (in other words based on the 
symmetrically completed ballots)
or Whole (so that truncated ballots give a whole vote to each of the 
bottom-counts of the truncated
candidates)?

In this case neither version eliminates C, but I'd be surprised if 
examples couldn't be made of
them also failing those criteria.

You implied that you are a fan of Later-no-Harm.  If that is the case I 
don't think you will find a better
method than plain IRV/RCV

Chris B.

> Here are 3 elimination-methods that eliminate 1 candidate at a time:
>
> …
>
> RCV/IRV:  Eliminates lowest topcount
>
> …
>
> Coombs: Eliminates highest bottomcount
>
> …
>
> Baldwin; Eliminates lowest Borda-score.
>
> …
>
> Any one of those can be the “base-method” .





> *Michael Ossipoff*email9648742 at gmail.com 
> <mailto:election-methods%40lists.electorama.com?Subject=Re%3A%20%5BEM%5D%20My%20CTE%20post%20to%20EM&In-Reply-To=%3CCAOKDY5CU-zc3Y%3DC%3DrFWagy3zVw5Px6KPaULqW89gHdxshRZh8A%40mail.gmail.com%3E>
> /Fri Oct 6 14:33:40 PDT 2023/
>
>
> ------------------------------------------------------------------------
>   When I said:
>
> "There’s no offensive strategy for changing the CW to one’s own favorite."
>
> I meant, there's no offensive strategy for changing the winner from the CW
> to one's own favorite.
>
> On Fri, Oct 6, 2023 at 5:21 PM Michael Ossipoff <email9648742 at gmail.com  <http://lists.electorama.com/listinfo.cgi/election-methods-electorama.com>>
> wrote:
>
> >/Name of Method: />//>/… />//>/CW,Takedown-Elimination (CTE) />//>/… />//>/or />//>/… />//>/Simmons-Ossipoff Method />//>/… />//>/Okay yes, I like the 2nd one. />//>/… />//>/It adds an enhancement to any of several already-existing />/elimination-methods. />//>/… />//>/Here are 3 elimination-methods that eliminate 1 candidate at a time: />//>/… />//>/RCV/IRV: Eliminates lowest topcount />//>/… />//>/Coombs: Eliminates highest bottomcount />//>/… />//>/Baldwin; Eliminates lowest Borda-score. />//>/… />//>/Any one of those can be the “base-method” . />//>/… />//>/Method rule: />//>/… />//>/Ranked balloting. Equal-rankng & truncation allowed. />//>/… />//>/1) Check for a CW & elect hir. />//>/… />//>/2) If none, do the base-method. />//>/… />//>/3) During the doing of the base-method: />//>/… />//>/When the base-method’s rule eliminates a candidate, eliminate 
> additionally />/anyone who is pair-beaten by that candidate. …& additionally any />/candidate beaten by that 2nd candidate. />//>/… />//>/That’s takedown & secondary takedown. />//>/… />//>/4) If anyone becomes un-pairbeaten due to elimination of who beats hir, />/s/he wins. />//>/… />//>/5) Continue till only one candidate remains uneliminated. />//>/… />//>/[end of count-rule definition] />//>/… />//>/Though it was Forest who introduced the unprecedentedly gamechanging />/Takedown, & applied it to Coombs & Baldwin, the bombast in this post 
> is all />/mine. />//>/… />//>/Obviously a CW wins if voting is sincere. />//>/… />//>/There’s no offensive strategy for changing the CW to one’s own favorite. />//>/… />//>/There’s no need for defensive strategy to protect the win of a CW. />//>/… />//>/While MinMax(wv), Schulze, RP(wv) & Smith//MinMax(wv) require defensive />/truncation to deter burial strategy against the CW, the above-defined />/method requires no such defensive strategy, & voters can rank all the 
> way />/down to the bottom if they want to. />//>//>/PS. I added a statement that, for the purposes of takedown & secondary />/takedown, "pair-beaten" should probably mean "pairbeaten according to 
> the />/rankings before any eliminations." />//>/… />//>/Michael Ossipoff/
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