[EM] "we only get one shot" (Re: RCV Challenge)

[Richard Lung]

Thank you, nothing to do with Mr Coombs.

Binomial stv is monotonic: it gives well behaved results. Switching 
votes to a candidate can not perversely help lose them the election. 
Because, the candidates keep values are re-calculated accordingly.

Switching the quota from Hare to Droop etc does not change the order of 
merit of the candidates (tho technically it changes their electibility).

There is no premature exclusion (or election) of candidates. The result 
depends on their over-all keep values, after all the preferences have 
been counted forward (electively) and backward (exclusively).

Regards,

Richard Lung.


On 05/01/2022 12:30, Kristofer Munsterhjelm wrote:
> On 05.01.2022 04:35, Forest Simmons wrote:
>> Kristofer and All,
>>
>> What I get from this is to use a Coombs/STV hybrid. Perhaps mostly
>> Coombs for Elimination and STV quotas for election ... something like that.
> It's a perhaps surprising but still nice observation that it doesn't
> matter how you eliminate candidates in STV as far as the DPC is
> concerned: as long as you do it one at a time, the criterion still holds
> because the election condition only looks at first preferences.
>
> I like the idea of using Ranked Pairs to determine the elimination
> order. Because RP passes LIIA, this gets rid of a major source of chaos
> in STV/IRV because the eliminations don't change the social order. Only
> the election and surplus distribution steps do that.
>
> It may be a mar on the perfect proportionality of STV that Ranked Pairs
> has a centrist bias (since it's a single-winner election method), and
> thus RP-STV would have some element of centrist/consensus bias. On the
> other hand, you could cast this as a feature rather than a bug: there's
> certainly no lack of polarization in the current political world, so
> perhaps a bit of centrist/consensus bias is not so bad.
>
>
> As for Coombs STV, that's certainly one possible interpretation of
> binomial STV. But if binomial STV *is* Coombs STV, then it definitely
> isn't monotone, because in the single-winner case it's just regular old
> Coombs.
>
> -km