On Thu, Nov 10, 2022, 9:40 PM Richard, the VoteFair guy <
electionmethods@votefair.org> wrote:
On 11/9/2022 12:05 AM, Forest Simmons wrote:
A candidate is uncovered iff it has a beatpath of
only two steps to each candidate (if any) that beats it.
Should the "only two steps" be interpreted as "two or fewer steps?" or
"two or more steps?" or "exactly two steps?"
In this context, exactly two, because when a candidate beats it, it cannot
beat that candidate in one step, since it is not possible for X to outrank
Y on more ballots than Y outranks X, and at the same time have Y out rank X
on more ballots than X outranks Y.
A candidate X has a beatpath to every other candidate if and only if X is
in the Smith set.
So the Landau is a subset of the Smith set.
You see Landau is more special because it requires shorter beatpaths. Any
length beatpath will do for Smith.
Suppose the cycle ABCA is augmented with a candidate D that beats only A,
and is beaten by B and C.
Then all four candidates are in Smith because the beat cycle DABCD
includes a beatpath from each candidate to each of the other candidates.
Is D a Landau candidate? Well C beats it. So does it have a two-step path
back to C? No. So it is covered by C, and covered means not in Landau.
Is A a Landau candidate? Yes. Only D and C beat it, and ABD and ABC are the
respective required two-step beatpaths that get back to D and C,
respectively.
Does that help?
I'm still trying to understand the "uncovered" (and "covered") concept.
Especially, what is its relationship to the Smith set?
Thanks,
Richard Fobes
On 11/9/2022 12:05 AM, Forest Simmons wrote:
In this context the most relevant question is what do we mean by
"uncovered", since that's the word used in the method definition ...
Repeatedly eliminate the (remaining) candidate with fewest votes until
there remains only one uncovered candidate to elect.
No need to know what covering means, although you can figure it out
indirectly from the definition of "uncovered:"
A candidate is uncovered iff it has a beatpath of only two steps to each
candidate (if any) that beats it.
Any candidate X who complains that they should have won because they
beat the winner W pairwise will get this truthful and obviously relevant
rejoinder:
When you were eliminated, you had fewer transferred votes than I.
I fact, I beat every candidate pairwise that was not already eliminated
(like you) on the basis of two few (transferred) votes.
It is very easy to discern if some candidate X is uncovered:
Just check each candidate Y that beats it (X) to see if it has a two
step beatpath via some Z, back to Y:
X beats Z beats Y
Only Smith candidates can be uncovered because only Smith candidates
have beatpaths back to the candidates that beat them. So the candidates
you have to check are the Smith candidates ... at most three, and rarely
more than one, in a public election.
If you want, you can run IRV all the way through ... then if the IRV
winner is uncovered, you are done. If not, back up until you cone to an
uncovered candidate ... that's your winner!
It's just a matter of doing regular IRV, and backing up (if necessary)
until you get to an uncovered candidate.
Forest
On Tue, Nov 8, 2022, 11:18 AM Kristofer Munsterhjelm
<km_elmet@t-online.de mailto:km_elmet@t-online.de> wrote:
On 08.11.2022 18:02, Richard, the VoteFair guy wrote:
Forest, what do you mean by "covered"? Is there a Wikipedia or
Electowiki article (or section of an article) that explains it?
Or is
there a dictionary reference you can point to?
Yes, you've used the words "covered" and "uncovered" many times
but I
don't recall ever seeing a clear explanation of what you mean. I
presume it involves pairwise counts, but that's as far as I can
guess.
The short answer is: A covers B if A pairwise beats everybody B
pairwise
beats and then some.
An uncovered candidate is someone who is not covered by anyone else.
This definition works when there are no pairwise ties. Things get
trickier with pairwise ties, as I found out when generalizing
Friendly
Cover.
-km
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Grammatical correction...
On Sat, Nov 12, 2022, 6:28 PM Forest Simmons forest.simmons21@gmail.com
wrote:
I tried to state the most understandable description possible of Gross
Loser Elimination ... is the following version an improvement? Anybody have
a simpler or clearer description?
Suppose there are seven candidates. Each candidate gets six cards with
their name at the top and one of the other candidate names just below it.
Each card is given to a different election worker.
Pretend you are in charge of the card with Diane at the top and Jenny just
below it.
As the ballots are slowly opened one by one in a public ceremony so that
everybody can see each ballot on an overhead projector screen, you put a
hash mark on your Diane/Jenny card every time a ballot is opened that shows
a vote for Diane over Jenny.
After the ballots have been tallied in this way, you total the votes, and
put that vote total to the left of her name on the top left of your card.
This is the total of her votes in her matchup against one of the other
candidates, namely Jenny.
Then you hand in your card to the head vote counter, who sorts the cards
in order of the vote totals in the upper left corner of each card.
Now the Elimination steps:
Remove the card from the bottom of the stack, the one with the smallest
vote total next to the name at the top of that card. That name identifies
the Gross Loser. Eliminate all of the cards
that have that name anywhere on it.
Should be "on them" not "on it"
That concludes one step of GLE, Gross Loser Elimination.
Now remove the card from the bottom of the remaining deck. The name at
the top of that card is the Gross Loser name for this step.. Eliminate all
of the cards that have that name anywhere on it. That concludes another
step of GLE, Gross Loser Elimination.
Now remove the card from the bottom of the remaining deck. The name at
the top of that card is the Gross Loser name for this step.. Eliminate all
of the cards that have that name anywhere on it. That concludes another
step of GLE, Gross Loser Elimination.
Continue in this manner until all cards but two have been eliminated.
Eliminate the bottom of these two, and elect the candidate whose name is at
the top of the remaining card. This is the only candidate that was never at
any stage the worst of the worst ... i.e. never the Gross Loser.
-Forest
On Sat, Nov 12, 2022, 12:13 PM Forest Simmons forest.simmons21@gmail.com
wrote:
Q&D was the simplest way to always get the same result (when the Smith
set was four or fewer members) as Implicit Approval Chain Climbing ... a
monotonic, clone free, burial resistant, Banks efficient method ... as
simple as possible for a method with those criteria compliances ....
compliances that no other method on record could truthfully claim.
So why did it get no traction?
According guys "in the trenches" it has to be an elimination method with
vote transfers between steps.
No such method is monotonic, but the next best thing is Yee/Bolson
monotonic.
That method is Gross Loser Elimination (GLE).
The Gross Loser of a Round Robin tournament is the player whose worst
score (for any of her matchups) is worse than anybody elses's ... we could
call her the MinMin loser.
GLM is the elimination method that at each stage eliminates the gross
loser of the remaing candidates ... after the gross losers from the
previous stages have already been removed. The last candidate standing is
the winner.
As a reminder, the gross loser is the candidate with the worst worst
score. Each candidate has several scores ... one against each of the other
players. The worst of these is that candidate's worst score. The candidate
whose worst score is worse than anybody elses's worst score is the gross
loser. That is the one to be eliminated in the first step.
In the second step each candidate has a worst score in any of its
matchups with the remaining candidates. The candidate whose worst score is
worse than any other remaining candidate's worst score is the gross loser
of that stage. That's the one to be eliminated at that stage.
For example suppose that in 10th stage there are only four candidates
left ... candidates A B,C,&D with respective worst matchup scores of 15,
13, 28, and 35. Which one do you think would be eliminated at that stage?
If you guessed candidate B, you guessed right: B's worst score (13) at
this stage is worse (smaller than) any of the other three scores 15, 28, or
35.
Each elimination step is that simple!
Where do the matchup scores come from? In a sports tournament it is
obvious because each matchup is a completion for points.
In an election each matchup is also a competition for points ... in the
form of ........ (you guessed it) votes!
The scores we've been talking about are the votes in the head-to-head
matchups.
The beauty of RCV ballots is that for each matchup you can figure out the
scores for both candidates from the RCV ballots.
Suppose the matchup in question is between candidates X and Y.
Separate the ballots into three stacks.
Pretend that all of the other candidates are out of the picture so that
all votes are transferred to X and Y. How many votes would X get? That is
X's score for this matchup.
You don't have to actually deface the ballots by crossing out the
irrelevant candidates to find X's vote totals. Just count the number of
ballots on which candidate X outranks candidate Y.
This can be done for each of X's matchups, giving a complete set of
matchup scores for X.
Similarly we can get a completes set of matchup scores for each of the
other candidates.
And the one whose worst score is worse than anybody elses's worst score
is the Gross Loser.
So, to recap the method ... in the very first step eliminate the Gross
Loser. In the next step eliminate the Gross Loser from among the remaining
candidates, those who were not eliminated in the first step.
In all subsequent steps where more than two candidates remain, eliminate
the Gross Loser from among those remaining candidates.
When it gets down to two candidates eliminate the Gross Loser, the one
with the lowest score, i.e. the one with the fewest votes, i.e. elect the
one with the most votes in this final matchup.
This spells it out as plainly as I can do in the abstract. But what we
all know is children do not learn how to play a game by reading the
instructions on the inside cover of the box. They learn by playing with
friends who already know the rules.
This little card game (ballot counting game) is much simpler than
Monopoly, Poker, Uno, Clue, etc that kids feel pretty confident with after
a couple of dry runs with their friends.
A YouTube video is the second best way to teach it.
An EM text message is the worst way to teach it ... but you guys pick
things up faster than average!
-Forest
On Thu, Nov 10, 2022, 9:07 AM Toby Pereira tdp201b@yahoo.co.uk wrote:
So do you have a nice and simple definition of this method that anyone
can understand?
Where do you now stand on your Quick and Clean Burial Resistant Smith
method? At the time, it seemed to be the best thing since sliced bread, but
amongst all the posts, it now it appears not to have resisted, er, burial.
Toby
On Wednesday, 9 November 2022 at 22:07:53 GMT, Forest Simmons <
forest.simmons21@gmail.com> wrote:
I forgot to mention that Gross Loser Elimination is just as burial
resistant and Chicken resistant as IRV, and is less susceptible to
compromise than IRV, because unlike IRV, it has no Central Squeeze
pathology.
Imagine candidates X and Y close to the left and right of Center Z.
Under sincere ranked ballots Z will have few first choice votes compared to
X and Y, so it will be eliminated, unless one of the factions compromises
and votes its second choice Z over its favorite.
Which one would benefit by that insincere order reversal?
Answer: the pairwise loser in the final runoff step between X and Y.
A note on counting GLE.... a rectangular table of pairwise counts is
projected on the screen in the public counting room.
The k_th entry in the j_th row of the table is the number of ballots on
which the j_th candidate out ranks the k_th candidate.
As the ballots are opened and the candidate rankings carefully compared
one-by-one, the respective table entries for row j are incremental for each
candidate k that candidate j outranks on that ballot.
When the ballots have been fully tabulated, the elimination steps begin.
At each step the smallest entry in the table is circled. All viewers
must agree that it is indeed the smallest entry before continuing the step.
Once all observers are in agreement that the smallest entry is the k_th
entry of row j, then candidate j is declared to be the Gross Loser of this
step, and so is eliminated by crossing out both the j_th row and the j_th
column of the table.
The remaining table has one fewer row and one fewer column.
Find the Gross Loser of this smaller table by identifying which row has
the smallest entry, etc.
The last candidate standing is the GLE winner.
If you want the frosting on the cake, have a representative for each
candidate announce if they claim to have the highest uncovered candidate in
the finish order.
Process these claims in the reverse order, beginning with the GLE
winner, then the runner up, etc until either a claim is verified, or all
have been checked and refuted.
To check a claim X, those who challenge X must produce a candidate Y who
beats X, but is not at the end of a two step beat path from X to Y.
If the challengers cannot successfully refute the claim in this manner,
then the claim stands approved, and X is the winner.
In other words, elect the candidate with the first unrefutted claim in
the order of claim processing ... which (as we have already specified) is
the reverse of the elimination order.
Anybody have a better suggestion?
Nobody?
OK, then...how do we get the proposal ball rolling?
-Forest
On Wed, Nov 9, 2022, 8:50 AM Forest Simmons forest.simmons21@gmail.com
wrote:
This same simple tweak works on any method with a built in finish order,
including any one-at-a-time elimination method like IRV, BTR-IRV, Baldwin,
etc:
Elect the uncovered candidate highest in the finish order.
Why does our suggested tweak say to elect the highest uncovered
candidate in the finish order, instead of the highest unbeaten candidate in
the finish order?
Answer: because sometimes there is no unbeaten candidate, but there is
always an uncovered candidate.
The simplest and best one-by-one elimination method is Gross Loser
Elimination.
No other one-at-time elimination method can improve on it, much less the
uncovered version:
Elect the uncovered candidate highest in the Gross Elimination finish
order.
Like IRV it is clone free. Unlike IRV it is precinct summable on one
pass through the ballots at each precinct.
Wouldn't that have been nice last night at the midterm election count?
Like IRV it is non monotonic, but unlike IRV it is Yee/Bolson monotonic:
the win regions are convex, not pathological fractals. [I almost wrote
Bolsonaro instead of Bolson ... sorry Brian!]
Pick any method X, and pair it with Gross Loser Elimination ...
uncovered version or not ... and do a pairwise runoff between the two
winners.
Not only will Gross Loser Elimination almost always come out ahead, the
people who do the experiment will come away saying, "Why do we even bother
with method X? GLE is so much more simple and effective."
GLE is already Smith efficient without the uncovered tweak ... that's
just optional frosting on the cake.
It is the simplest Smith efficient method that does not require
computing pairwise wins or losses. No need to mention Smith or Condorcet or
pairwise defeats.
It automatically eliminates the Condorcet Loser at any stage when there
is one, because when there is a Condorcet Loser, it will also be the Gross
Loser.
The Gross Loser is the candidate with the fewest ballots preferring it
over any other candidate. In a tournament, it is the candidate with the
single most embarrassingly low score.
In fact, unlike IRV, Gross Loser Elimination can be used to get a finish
order for a Round Robin Tournament, so the uncovered tweak can be applied
to it if so desired.
Suppose when there are only three uneliminated teams, team Rock's scores
against the other two teams stand at 60 and 40, while team Paper's scores
are 45 points against one team, and 72 against the other, and finally team
Scissors' scores stand at 35 and 90.
Which team will be eliminated at this stage of GLE?
Answer ... Scissors, because no other team scored as low as 35.
Note that we did not even need to know who the other team was that
skunked Scissors, or how much it scored in that game to know that Scissors
was the Gross Loser of that round.
Now tell me, who was the IRV loser of that round?
Answer: impossible to know, because IRV makes no sense in a tournament
context, unless it is a superficial popularity contest of some kind.
Is this the best RCV public proposal?
No other Universal Domain method this simple is anywhere near as good.
How about outside the UD? Do you think STAR is a better proposal? If so
why?
-Forest
On Wed, Nov 9, 2022, 12:05 AM Forest Simmons forest.simmons21@gmail.com
wrote:
In this context the most relevant question is what do we mean by
"uncovered", since that's the word used in the method definition ...
Repeatedly eliminate the (remaining) candidate with fewest votes until
there remains only one uncovered candidate to elect.
No need to know what covering means, although you can figure it out
indirectly from the definition of "uncovered:"
A candidate is uncovered iff it has a beatpath of only two steps to each
candidate (if any) that beats it.
Any candidate X who complains that they should have won because they
beat the winner W pairwise will get this truthful and obviously relevant
rejoinder:
When you were eliminated, you had fewer transferred votes than I.
I fact, I beat every candidate pairwise that was not already eliminated
(like you) on the basis of two few (transferred) votes.
It is very easy to discern if some candidate X is uncovered:
Just check each candidate Y that beats it (X) to see if it has a two
step beatpath via some Z, back to Y:
X beats Z beats Y
Only Smith candidates can be uncovered because only Smith candidates
have beatpaths back to the candidates that beat them. So the candidates you
have to check are the Smith candidates ... at most three, and rarely more
than one, in a public election.
If you want, you can run IRV all the way through ... then if the IRV
winner is uncovered, you are done. If not, back up until you cone to an
uncovered candidate ... that's your winner!
It's just a matter of doing regular IRV, and backing up (if necessary)
until you get to an uncovered candidate.
Forest
On Tue, Nov 8, 2022, 11:18 AM Kristofer Munsterhjelm <
km_elmet@t-online.de> wrote:
On 08.11.2022 18:02, Richard, the VoteFair guy wrote:
Forest, what do you mean by "covered"? Is there a Wikipedia or
Electowiki article (or section of an article) that explains it? Or is
there a dictionary reference you can point to?
Yes, you've used the words "covered" and "uncovered" many times but I
don't recall ever seeing a clear explanation of what you mean. I
presume it involves pairwise counts, but that's as far as I can guess.
The short answer is: A covers B if A pairwise beats everybody B pairwise
beats and then some.
An uncovered candidate is someone who is not covered by anyone else.
This definition works when there are no pairwise ties. Things get
trickier with pairwise ties, as I found out when generalizing Friendly
Cover.
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It may surprise you that given the same agenda, SPE (Sequential Pairwise
Elimination) and Highest Uncovered are extremely hard to differentiate.
There has probably never been an actual ballot set where they would elect a
different candidate from the same agenda order.
Certainly none of Kevin's seven taxonomical examples could do it because
they all involve Smith sets of only three members ... in which case it is
easy to show that the two methods will always agree.
Here 's the demonstration:
First, both methods are ISDA.
SPE is IPDA because nonSmith candidates have no influence on the pairwise
sorting of Smith, which always comes out solid ahead of the other
candidates no matter what the sorting priority rule ... top, bottom,
margins, etc.
Highest Uncovered is ISDA because only Smith members can be uncovered ...
so electing the highest uncovered agenda item is the same as electing the
highest uncovered Smith item on the agenda.
This brings us the next point: when there are only three Smith members, all
of them are uncovered. This is because all Smith members have beatpaths to
all other Smith members, and when there are few Smith members those
beatpaths must be short (or unnecessarily repetitious)... in this case only
one or two steps are possible without unnecessary repetition.
The only remaining questionis which member of a three member Smith does SPE
elect.
Suppose the three members are X , Y and Z, and that their cyclic order is
XYZX. If the agenda order is in agreement with cyclic order, pairwise
sorting will not change it, so the highest agenda Smith candidate is the
SPE winner.
What if the agenda order is not the pairwise cyclic order?
Then, since SPE goes from bottom to top, it will switch the order of the
bottom two Smith members. That switch puts Smith into cyclic order so no
further change in the order of Smith. The highest agenda Smith candidate
gets elected, as in Highest Uncovered.
In sum, when Smith has three members, SPE and Highest Uncovered both elect
the top Smith candidate in the sgenda.
Since SPE and Highest Uncovered are both equally easy to compute, the main
question is what is the best agenda?
Colin proposed basing the agenda on first place votes, but that is subject
to note splitting (our only good reason for abandoning simple, traditional
FPP Plurality) Here's an example that shows the vote splitting problem:
21 A1>B>C
19 A2>B>C
35 B>C>A1
33 C>A2>A1
The agenda order is B>C>A1>A2.
B is both the SPE winner and the Highest Uncovered agenda winner, as well
as the winner of Ranked Pairs, River, Schulze, and many other methods
including IRV.
If A had not been split into A1 and A2, the agenda would have been A>B>C,
and the winner of all the aforementioned methods would have been A.
So that's why I suggested Implici Approval: If they are not going to allow
us to rank more than three candidates, then the simplest agenda method that
avoids vote splitting is the implicit approval agenda ... the candidates
most favored by the agenda are the ones unranked on the fewest ballots.
Since you cannot rank all of the candidates leave the candidates that least
approve of unranked.
Although that's the simplest acceptable agenda in this context (of forced
truncations) there may be another that is worth the extra complexity.
-Forest
On Sat, Nov 12, 2022, 12:00 AM Forest Simmons forest.simmons21@gmail.com
wrote:
Evidently the IRV proposers hacve had to settle for ránking only there or
tour candidateson each ballot ... better than nothing.
One pass through the ballots to get the pairwise information and the
number of truncations for each candidate ... the exact same work as the SPE
method you propose ... but an agenda of first place votes breeds lots of
vote splitting unless you expect the voters to have lots of equal first
rankings ... not a good idea.
Electing the uncovered candidate unranked on the fewest ballots is a
simpler Condorcet method than SPE ... and it is guaranteed to elect an
uncovered member of the Smith Set.
But SPE is also good ... if the agenda is clone independent, like implicit
approval.
-Forest
On Fri, Nov 11, 2022, 5:26 PM Colin Champion <
colin.champion@routemaster.app> wrote:
On 11/11/2022 20:49, Forest Simmons wrote:
Since almost all RCV implementations limit the number of candidates
that can be ranked on a ballot, the simplest decent RCV method is ...
Elect the uncovered candidate that is unranked on the fewest ballot
Does anyone know why this truncation is imposed? If it’s to limit the
amount of work needed to count the ballots, wouldn’t it make sense for
Condorcet supporters to advocate a method which was countable in linear
time? In practice this would presumably be Sequential Pairwise
Elimination with an FPTP pre-ranking. If you insist on a quadratic time
method and accept the corollary of ballot truncation, I don’t imagine it
will work very well. Or am I missing something?
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On 14/11/2022 03:54, Forest Simmons wrote..
many wise things
I think Forest slightly missed my point - I was arguing that SPE could
be proposed as an alternative to truncation, since I surmised
(incorrectly) that truncation might have been justified by a desire to
avoid quadratic counting costs. Hence there would be no cutoff as part
of the voting procedure, and no natural concept of implicit approval. If
there is political opposition to mechanical counting, then proposing a
linear-time countable method seems to me better than either putting up
with truncation or fighting unnecessary battles.
I don't know why linear-time countability dropped out of consideration.
In 1275 Llull proposed the "league table" method now often named after
Copeland, but with one difference - he didn't suggest ranked preference
voting (after all, paper hadn't been invented then, let alone
computers). Instead he called for m(m-1)/2 pairwise subelections. In
1299, presumably recognising the unworkability of this, he proposed a
"knockout" method comprising just m-1 pairwise subelections which
amounts to SPE with an arbitrary agenda. I think this was in one of his
writings which got lost.
A little later, taking advantage of the invention of paper, Nicholas
of Cusa proposed the Borda count in conjunction with ranked preference
voting. Borda reinvented his ideas in the 18th century. Condorcet (in
his Essai) got bogged down in problems arising from cycles, and
partially extricated himself with a quadratic-time algorithm which is a
simplified ranked pairs. In his later writings he reinvented Llull's
league table method and instantly rejected it on account of its
quadratic cost. In its place he advocated what I take to be a defective
form of Bucklin's method.[1] This was adopted in Geneva and "found not
to work" (I don't know the details, but Bucklin's method is quite a
large step backwards).
Nanson carried on from Condorcet. He agreed that the quadratic cost
made Llull's league table unworkable, wasn't attracted to Bucklin's
method, and instead proposed his own. He may have been a little
optimistic in his costings, but at worst his method is m log m.
That seems to be the end of the discussion. When Black proposed his
method in the middle of the last century, voting technology was no
different than in Condorcet's day, but he doesn't seem to have worried
about the counting costs. Llull's knockout reappeared as SPE with a
pre-ranking stage to eliminate the obvious asymmetry, but since
quadratic-time pre-rankings are often assumed, counting time hasn't
always been the main consideration.
CJC
[1]. I always confuse Bucklin's method with Baldwin's. I wish the latter
was called the "Trinity College" method, since it was invented before
Baldwin's time. The Trinity College Dialectic Society was founded at
Nanson's university a few years before Nanson wrote his memoir, so its
voting method was presumably an early version of Nanson's.