[EM] Hay guys, look at this...

[Forest Simmons]

Colin,

You just floated a bunch of methods that are way more complicated and
objectively inferior in results compared to the specific method I
suggested, as well as compared to many other methods of the same type:

Absent a CW elect the candidate with the strongest defeat strength ...
period.

All of the other good methods that actually rival my suggestion in
simplicity (by not introducing elimination steps, approval cutoffs, scores,
equal-first rankings, etc.) are of this type ... I have wasted a lot of
time time looking elsewhere.

Here's a slightly less simple example of this promising type ...

Absent a CW, elect the strongest defeat winner where strength of defeat is
gauged by ... winning votes plus losing truncations.

Each pairwise defeat has a winner and a loser ... winning votes (wv) means
the pairwise support of the winner, i.e. the number of ballots on which the
winner out ranks the loser.

Losing truncations simply means the number of ballots on which the Loser is
unranked.

Let's look at our two previous examples in this light ...

48 C
28 A>B
24 B

A defeats B with strength 28 winning votes plus 48 losing truncations ... a
total strength of 76.

B beats C with 52 wv  plus 52 losing truncations ... 104 total.

C beats A with total strength 48 plus 72, or 120.

So again, the Plurality winner C has the strongest defeat over any other
candidate by this wv+losing truncations gauge.

Example2:

40 A>B
35 B>C
25 C

A beats B with strength 40 wv plus 25 loser truncations... 65 total.

B beats C with 75 wv plus 40 truncations ... a total strength of 115.

C beats A with 60 wv plus 60 truncations. C wins.

If the C faction truncated A in anticipation of the A faction's burial of
C, it worked ... the defensive truncation saved the sincere CW.

This is (arguably) a strategic improvement over our slightly simpler
margins (wv minus lv) gauge that I am still recommending.

It's like the difference between an error detecting code and an error
correcting code.

-Forest

On Sat, Feb 18, 2023, 9:54 AM Colin Champion <colin.champion at routemaster.app>
wrote:

> Kristofer - firstly an apology, I gave the result for Condorcet//fptp
> rather than Condorcet,fptp. The correct results are: minimax 64%,
> condorcet+fptp 59%, copeland,fptp 53% (vice 47%).
>    As for other good, simple methods, I find it hard to say. Lots of
> reasonably accurate methods are aesthetically objectionable for a range of
> reasons; for instance I think that Condorcet+random is at least as good as
> Condorcet+fptp (presumably because it's hard to manipulate), but no one
> would be happy to see so prominent a role given to chance.
>    'Minisum' - which I think is the same as Tideman's "Simplified Dodgson
> Rule" - is almost as good as minimax, but I can't see why anyone would
> choose it in preference (it looks rather similar). It has the drawback of
> having received little discussion in the literature.
>    Copeland,dblv is somewhat better than Copeland,fptp. The double vote
> elects the candidate with the greatest sum of first and second preferences.
> It's a lousy voting method but an effective tie-break because it tends to
> blow up in the face of anyone who attempts tactical voting.
>    Copeland,minimax is very good, but again why bother? Its resistance to
> tactical voting comes from minimax; Copeland's method is little more than a
> sleeping partner.
>    Copeland//Borda (which is one interpretation of Dasgupta/Maskin) is
> probably slightly better than Copeland,fptp.
>    Benham's method and Black's are both pretty good. So are some of the
> more complicated methods such as RP.
>
> All this subject to the usual caveats about software reliablilty. The
> results table is at
> https://www.masterlyinactivity.com/condorcet/condorcet.html#results
>    Colin
>
> On 18/02/2023 11:47, Kristofer Munsterhjelm wrote:
>
> On 2/18/23 10:42, Colin Champion wrote:
>
>     But then I don't favour Kristofer's proposal either. My evaluation
> suggests that burial is a particular threat for Condorcet methods, and that
> in its presence their accuracies are: minimax 64%, condorcet+fptp 59%,
> copeland,fptp 48%. [Usual disclaimers apply.]
>
>
> That's fair; I was simply trying to find a minimal change to the method
> that would at least grant Smith or something like it.
>
> Really, what I'm concerned about is that there's such a, for lack of a
> better term, steep cliff from the Condorcet domain down to the Plurality
> domain. So everything's nice as long as you play on top of the mountain,
> but if you misstep (i.e. produce a cycle), then you don't gradually
> degrade, you fall directly into plain old Plurality, with all of its vote
> splitting problems. The discontinuity seems like something that's just
> asking to be exploited.
>
> Do you know of any alternate "bang for the buck" methods that would be
> simple enough to be accepted?
>
> -km
>
>
> ----
> Election-Methods mailing list - see https://electorama.com/em for list
> info
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.electorama.com/pipermail/election-methods-electorama.com/attachments/20230218/9fd90814/attachment-0001.htm>