[EM] Summability criterion: do I have this right?

[Michael Ossipoff]

All methods require counting at the precincts & at Central.

Runoff & STAR require information be sent from Central back to the
precincts where an additional count is done, whose results are again sent
to Central for another count.

RCV is like Runoff & STAR, but the process is repeated. More times, but not
really a qualitative difference.

On Thu, Oct 5, 2023 at 21:46 Rob Lanphier <roblan at gmail.com> wrote:

> Hi folks,
>
> I've made a change to electowiki's "Summability criterion" article:
> https://electowiki.org/wiki/Summability_criterion
>
> Here's the chunk that I added:
>
>> For batch summability to be true, the following must be true:
>>
>>    - Say that candidates "A", "B", and "C" run against each other in an
>>    arbitrary election using single-winner electoral system "S"
>>    - Say that candidate "A" wins in batch "X" (or precinct "X") when
>>    ballots are tabulated using single-winner electoral system "S"
>>    - Say that candidate "A" wins in batch "Y" (or precinct "Y") when
>>    ballots are tabulated using single-winner electoral system "S"
>>    - Therefore, candidate "A" must win when batches "X" and "Y" of
>>    ballots are tabulated using single-winner electoral system "S" for "S" to
>>    be "batch summable" (and thus, pass the "summability criterion")
>>
>> (end of definition)
>
> Am I correct?  I'm trying to come up with a definition that is easy enough
> for a layperson to understand, but is also accurate.  I realize that this
> definition only captures a subset of elections that demonstrate summability
> problems, but this seems (to me) like the core of the problem with
> summability.
>
> Rob
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