[EM] Easy River definition (also my site is back up)

[Michael Ossipoff]

Wow. River doesn’t need the exhaustive pairwise-count? How does its
count-time compare to that of RP?

I didn’t know that about River. I believed that only Sequential-Pairwise
was the only exception to the need for the exhaustive pairwise-count.

The exhaustive count requires, per voter, counting one pairwise-vote for
each possible pair of candidates.

How many votes need to be counted per voter in River?

If one only cares about finding the winner, rather than an output-ranking,
could the count-instruction be written more briefly?

As written, it’s much too complicated for a public-proposal.

Someone said that River is better at deterring burial. I disagree. It seems
to me that skipping a defeat if its defeated is defeated in an already-kept
defeat undermines autodeterence.

Only one of the CW’s defeats is kept. That means that every Bus but one
can’t have its defeat dropped, so only one Bus survives.

I like it if the exhaustive pairwise-count isn’t needed, but can the
count-instructions be written more briefly, if only the winner is needed?

On Sat, Mar 9, 2024 at 07:02 Kevin Venzke <stepjak at yahoo.fr> wrote:

> Hi Mike and everyone,
>
> First off, if anyone was missing my site, it is back up. I had to find
> different
> hosting (a bit abruptly).
>
> Where I was trying to link right before the site went down:
> votingmethods.net/cond
> works out a given (or random) scenario for Schulze, RP, or River. You just
> have to
> expand sections at the bottom of the result. So it could be worth a look.
>
> Mike wrote:
> > Is River as easy to define &. explain as RP?.
>
> I see I should try to write out clearly how I suggest to understand River.
>
> There is no "final ranking" in River. Instead every candidate begins
> "below no one"
> or "subordinated to no one." This is sort of a ranking but the "trees" we
> make go
> only one level down: you will never be able to ascend two positions from a
> given
> candidate.
>
> 1. Initially each candidate is subordinated to no one.
> 2. Consider each pairwise defeat from strongest to weakest.
> 3. When you consider a defeat, ask whether the loser is subordinated to
> anyone?
> If so: Ignore the defeat and proceed to the next.
> If not, then ask:
> 4. Is the defeat winner subordinated to the defeat loser? If so, ignore
> the defeat
> and go to the next.
> 5. Is the defeat winner subordinated to someone else? If so, the defeat
> loser, along
> with everyone subordinated to them, becomes subordinated to the candidate
> that the
> defeat winner is subordinated to.
> 6. Otherwise it must be that the defeat winner is subordinated to no one.
> So here
> the defeat loser, along with everyone subordinated to them, becomes
> subordinated to
> the defeat winner.
> 7. End loop. Go to the next defeat.
> 8. In the end, the candidates subordinated to no one are the winners.
>
> Alternatively instead of talking about subordination, you can say that each
> candidate has their own "bin" and starts in their own and may move to
> another.
> This would allow you to merge steps 4 and 5:
> "4. The defeat loser, along with everyone *in the loser's bin*, moves to
> whichever
> bin the defeat winner is currently located in."
> And if the latter bin happens to be the loser's bin, in effect nothing
> happens. We
> don't need a rule saying to ignore the defeat, because the bin movement
> doesn't
> change anything either.
>
> I can understand if a reader eyeballs all that and says this looks like a
> mess and
> it's not clearer than RP.
>
> But hear me out on the *ease* of it:
>
> 1. If you are programming River, you never actually check for a cycle,
> whether a
> proposed defeat would create one. And comparing to Schulze, you never
> trace a
> beatpath or find its strength, or (by its other algorithm) have to find
> the Schwartz
> set repeatedly.
> 2. If you are solving it by hand, it would be enough to have a fridge
> magnet for
> each candidate, start them out in imaginary bins, and push the magnets
> around in a
> straightforward way to track who is subordinated to whom.
>
> It may be possible to define RP more concisely, but it takes some work to
> figure out
> what it is actually saying to do to solve it.
>
> Hopefully the above explains it better than I have before.
>
> Kevin
> votingmethods.net
>
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