Good lord, why?!  I clicked on all the links but didn’t see any justification for this regressive move, though some of the linked documents are pretty long and I didn’t search through them exhaustively.

--pH

On 3/5/23 01:41, Hahn, Paul wrote:

I don't know; maybe we have to ask Max. He seems to be here:

https://www.facebook.com/max.holmes.56/ and
https://ca.linkedin.com/in/maximillian-holmes-2b9223132/

There might also be something buried in the minutes here, although I
really don't fancy trawling through all the documents:

https://www.ams.ubc.ca/about-us/student-council/agendas-presentations-minutes/

But at least there's one good thing about this being brought to our
attention - since the AMS used Ranked Pairs earlier, its earlier code of
procedures document gives a good example of legislative language for
implementing the Ranked Pairs method:

https://www.ams.ubc.ca/wp-content/uploads/2021/01/AMS-Code-Section-Nine-Dec-8-2020.pdf

which may be of interest to anyone who wants to propose Ranked Pairs as
a practical election method in his organization or city.

The Ranked Pairs description starts at PDF page 24 (document page 98),
after some general ranked ballot instructions on the page before it.

-km

Their specification doesn't say what to do if two pairs have equal
margins, although other forms of tie are at least vaguely described. I
assume "there is a tie" means "the margin is zero", but the language is
slightly misleading. Maybe whenever two pairs had equal margins the AMS
resorted to a coin toss between all candidates.

CJC

On 05/03/2023 10:28, Kristofer Munsterhjelm wrote:

Is it really regressive? People on this list have politics on their
minds and think of elections in terms of spatial models. Maybe a jury
model gives a better fit to AMS elections. If so, we don't need to worry
so much about the "center squeeze".
   CJC

On 05/03/2023 00:41, Hahn, Paul wrote:

Second thoughts – jury models are pretty useless: the role of chance in
them corresponds to nothing in reality.
   Another possibility is that elections satisfy a spatial model in
which the number of dimensions is equal to the number of candidates.
Perhaps there are 20 candidates at the points (0,0,0,... 1,... 0,0).
Voting is deterministic; I don't think there's any center squeeze; and I
suspect that IRV would be competitive with Condorcet voting.
   CJC

On 05/03/2023 11:15, Colin Champion wrote:

Hello,

Colin wrote:

Incidentally I think this is a considerable advantage of Schulze, that no matter which
approach you use, i.e. the beatpath algorithm or the Schwartz sequential dropping one, you
are able to go through the calculation a single time and you will know whether ultimately
there is a tie and who was in it.

I recently made a calculator that tries to show the steps to solve Ranked Pairs and River
and I couldn't come up with a satisfying way to dedupe all the possible ways that one could
traverse the propositions when there are tied strengths, and potentially many. I settled on
showing up to two traversals per possible winner.

Kristofer wrote under "Why all the fuss?":

Yes, implementing a complicated method can take some time, and I'm often unsure of the
prospects for a method to be good in some way. (This might even cause me to implement it
wrong due to bad intuition.)

I've seen skimming the recent posts that Forest is proposing a number of methods where
you're pretty much going to look at all the pairwise contests, and there are a number of
points within the course of following the algorithm where the method can take a turn and
lead to a change in outcome. I feel pretty confident at least that such a method, from a
burial incentive standpoint, is not going to be very interesting to Kristofer. It might
work for me, that's true.

One thing I could do is provide a bunch of examples on what methods look like in my
framework, taking the form of a Python 3 class, and then people could just send me methods
if they want. I'm not sure if there would be any takers for that. It would probably be more
interesting if I was maintaining and publishing a big list of results, which at the moment
I'm not. (Partly due to the sensitivity of results to scenario parameters.)

The idea of making some new visuals is interesting. I would like to somehow map the
correlations or apparent trade-offs present in methods' compromise, burial, and truncation
incentive. That's seemingly a 3D plot though.

Kevin
votingmethods.net

I think Tideman's original description calls for the implementor to
recursively exhaust over all permutations of tied margins, and to
construct a winner set as the union of winners under all recursive
extensions. This is no fun. The Handbook of Computational Social Choice
(one of my few books on the subject) says "Whether a given alternative
is a ranked pairs winner... turns out to be NP-complete". (p100.)
   I agree that Schulze's method cuts out a lot of pain. I don't think
Tideman himself ever proposed his method for practical use.
      CJC

On 06/03/2023 05:26, Kevin Venzke wrote:

On 06.03.2023 06:26, Kevin Venzke wrote:

IIRC, Tideman originally proposed a method where X wins if there exists
a way to break ties so that X comes unambiguously first in Ranked Pairs.
This method is neutral, but it's also (as Colin said) NP-complete. In
practice, people just break ties in some way. I think that the AMS
method (just a coin flip) fails clone independence and that random voter
hierarchy, while cloneproof, fails summability. But I'm not entirely
sure about either.

(E.g. part of my intuition says: "if you pick a random voter and rank
A>B over B>A if that voter ranks A over B... isn't that the same as a
coin toss? Because imagine you eliminate everybody but A and B, then the
number of voters who rank A above B is just A>B, and the number of
voters who rank B above A is B>A; and by presumption that there's a tie,
A>B must be equal to B>A, so the chance of picking a voter who prefers A
to B is 50%". If it were that simple, then there would be no need for
random voter hierarchy, so clearly I'm missing something.)

Maybe there exist cloneproof summable tiebreaking rules. But practically
speaking, I imagine public elections would produce enough noise in the
ballots that it would be very unlikely for two pairwise relations
involving candidates in the Smith set to have exactly equal strength.

I agree that Schulze doesn't have this problem, though I have the
impression it's considered to be more complex and harder to explain to
non-mathematicians. (However, the evidence is ambiguous: both Ranked
Pairs and Schulze have been used by organizations to do their elections.
And Schulze is used by a Spanish city for referenda, but I'm not aware
of any public elections using RP. So who knows?)

I've had similar ideas myself, that surely it should be possible to not
be duplicating each other's efforts as much. Strictly speaking, my
quadelect simulator is extensible, but I wouldn't call it very easy to
use and C++ has its own quirks.

Would you be interested in putting your code on a version control system
of some kind?

My Python voting simulator uses stacked bar charts to show
susceptibility to compromise, burial, and two-way strategy (both at
once). Unfortunately its results are sometimes wrong and I can't find
the bug that distorts them. But that might be a way to show just what
type of strategy works - e.g. Plurality is all compromise, Antiplurality
is all burial.

-km

On 06.03.2023 11:11, Colin Champion wrote:

Yeah, that's BRILL, Markus; FISCHER, Felix. The price of neutrality for
the ranked pairs method. In: Proceedings of the AAAI Conference on
Artificial Intelligence. 2012. p. 1299-1305.
https://ojs.aaai.org/index.php/AAAI/article/view/8250/8109

(I forgot to put that cite in my reply to Kevin, so here it goes :-)

I would expect that River is also NP-complete in the same way, but I
haven't seen any proofs to that end.

-km