Michael Christened our new Q&D burial resistant method "Duncan"...
What does "Q&D" mean?
Am I right in assuming that the Borda counts are based on the
symmetrically completed ballots?
Duncan Definition:
In the vast majority of the cases ... those in which the pairwise
counts of the ballots unambiguously identify the candidate that
pairbeats each of the others ... elect that candidate.
Otherwise, elect the highest score candidate that pairbeats every
candidate with lower score.
So another way of putting it is: "If there is no CW, elect the member
of the Smith set with the second-worst score".
To put it bluntly, that is bound to have monotonicity problems and
doesn't fly philosophically.
Trying to deter or frustrate order-reversal Burial strategy is fine, but
the algorithm should "appear fair" and be able to be justified when
we assume that all the votes are sincere (or even just all equally
likely to be sincere).
So if the score-order is A>B>C and there is a A>B>C>A top cycle (aka
Smith set) then this "Duncan" method elects B.
That breaks (at least one version of) "Double Defeat". B is pairwise
beaten by a candidate with a higher "score".
Chris B.
On 14/10/2023 4:43 am, Michael Ossipoff wrote:
Yes, I like Duncan because burying the CW in an attempt to help your
favorite won’t help hir when it causes hir disqualification, as it
probably will.
…& Duncan is remarkably briefly-defined, needing only a very slight
modification of Black’s method.
On Fri, Oct 13, 2023 at 10:11 Forest Simmons
forest.simmons21@gmail.com wrote:
Dear EM List Friends,
We need your feedback on this draft of a proposal before we submit
a version of it to the voting reform community at large.
---------- Forwarded message ---------
From: *Forest Simmons* <forest.simmons21@gmail.com>
Date: Thu, Oct 12, 2023, 5:35 PM
Subject: Duncan Proposal Draft
To: Michael Ossipoff <email9648742@gmail.com>
Michael Christened our new Q&D burial resistant method "Duncan"
after Duncan Black who popularized the idea of using Borda's
Method as a fallback "completion" when the ballots fail to
unambiguously reveal the sincere "Condorcet" pairbeats-all candidate.
Our Duncan method has the same form as Black's in that the
official version directly specifies electing the unambiguous
Condorcet Candidate when there is one, and falls back to another
procedure that relies on Borda Scores, otherwise.
It should be emphasized that in both cases the fall back Borda
based expedient is rarely needed. For that reason some misguided
voting reform advocates have cavalierly opined that any decisive
completion/ fallback method would be plenty adequate to supplement
the Condorcet Criterion requirement.
However, this casual attitude ignores the feedback aspects of
voting systems in that various voting methods vary in the degree
that they encourage or discourage the creation of artificial beat
cycles that subvert/ hide the Condorcet Candidate from view,
bringing the completion method into greater prominence in a
potentially unstable cycle.
Unfortunately most of the extant methods fall into this "positive"
feedback category, including Borda itself. Some less sensitive
methods like Approval and IRV/RCV have a built in "friction" that
dampens the feedback; but as systems engineers know, the high
performance components are the ones that need the addition of some
carefully engineered negative feedback "circuit" to stabilize the
system as a whole.
In our Condorcet Completion context, our use of the Borda Count
scores is carefully designed with that stabilizing influence in
mind: adventurous strategists who are aware of this feature, when
acting rationally will be deterred from creating these cycles that
come back to bite them. Those not aware will find out when their
ploys backfire or otherwise disappoint them.
How do these pesky cycles arise so easily in Borda and other rank
based methods?
Suppose that your personal preference schedule for the
alphabetized candidates looks like ...
A>C>X>Y>Z, and that C is the Condorcet Candidate projected to win
the election if nobody acts nefariously.
You, and like minded friends, get the idea to insincerely move
your second choice to the bottom of your ballot (so it now reads
A>X>Y>Z>C) ... not to be "nefarious" so much as to just increase
the winning chances of your favorite A.
Could this work?
Yes, under Black's method if your friends follow your lead, this
"nurial" of C under the "busses" X, Y, and Z, could easily subvert
one or more of C's pairwise victories over X,Y, and Z, into
defeats of C by them, thereby hiding C's identity of sincere
Universal "pairbeater" status to just one more member of a
"beatcycle" of the form A beats X beats Y beats Z beats C beats A.
Note that the buried candidate C still beats the buriers'
favorite, A ... because lowering C does not decrease the number
of ballots that support C over A ... which is how easily and
innocently beatcycles like this can be created in Condorcet style
elections ... at least in the absence of negative feedback from
the cycle resolution fallback method.
In traditional Black that fallback method is Borda. Does that fix
the problem? ... or does it exacerbate it.
Well ... the same burial that put C at disadvantage in the
pairwise contests with X thru Z, also lowered C's Borda score by 3
counts per ballot, and raised
the Borda score of each of X thru Z to the tune of one count per
ballot.
The likely outcome is that C will end up with the lowest score,
and come in last in the finish order.
By way of contrast, under our new Duncan method, the most likely
winner is X, and the least likely winner is A, the burier
faction's favorite ... thus disappointing the burier faction
supporters ... teaching them that if they try to outsmart new
Duncan with insincere ballot rankings, they are apt to end up
helping elect their third (or later) choice instead of their first
choice or their second choice ... the one that they so cleverly
buried (however innocently or without malice).
Too many dabblers in voting method reform (as well as most
professionals) are unaware of these dynamics.
But now, with your new understanding, you, at least, can become
part of the solution.
Duncan Definition:
In the vast majority of the cases ... those in which the pairwise
counts of the ballots unambiguously identify the candidate that
pairbeats each of the others ... elect that candidate.
Otherwise, elect the highest score candidate that pairbeats every
candidate with lower score.
[Nominally "score" = Borda Count, though STAR Voting scores, for
example, could also serve]
How does this Duncan fallback procedure work to prevent A from
getting elected in our scenario regarding A thru Z?
Well, could A pairbeat every lower score candidate? In particular,
could A pairbeat C, which is now at the bottom of the Borda score
pile ... certainly lower than A ...?
Well, remember that "C beats A" was the last step in the beatcycle
created by A's friends.
So A does not pairbeat every lower score candidate, and therefore
cannot win.
New Duncan is burial resistant.
Next time ... more examples and insights ...
fws
On Sat, Oct 21, 2023 at 11:05 C.Benham cbenham@adam.com.au wrote:
Am I right in assuming that the Borda counts are based on the symmetrically
completed ballots?
Are you referring to how equal-ranking is counted in Borda? I advocate
that, in these methods’ Borda-count, a ranking give each of its
ranked-candidates a number of points equal to the number of candidates in
the ranking who aren’t ranked over hir.
Duncan Definition:
In the vast majority of the cases ... those in which the pairwise counts
of the ballots unambiguously identify the candidate that pairbeats each of
the others ... elect that candidate.
Otherwise, elect the highest score candidate that pairbeats every
candidate with lower score.
So another way of putting it is: "If there is no CW, elect the member of
the Smith set with the second-worst score".
Would you mind telling why that’s another way of putting it?
To put it bluntly, that is bound to have monotonicity problems and doesn't
fly philosophically.
How doesn’t it fly philosophically?
Trying to deter or frustrate order-reversal Burial strategy is fine, but
the algorithm should "appear fair" and be able to be justified when
we assume that all the votes are sincere (or even just all equally likely
to be sincere).
Remember that sincere top-cycles are vanishingly rare. That’s why
Sequential-Pairwise’s Pareto failure isn’t important, & it’s why
MinMax(wv)’s Condorcet Loser failure isn’t important.
It matters much more what happens in a strategic cycle. Does the method
reward or penalize burial? …or neither?
Duncan tends to often do neither, because it will likely disqualify both
Bus & BF. (I defined those usages when I defined CTE.
I prefer CTE to Duncan, because it more often penalizes, instead of merely
not rewarding.
But I remind you that these methods are intended to deter
probabilisticallly, but aren’t claimed to penalize burial in every possible
example.
That breaks (at least one version of) "Double Defeat". B is pairwise
beaten by a candidate with a higher "score".
Chris B.
On 14/10/2023 4:43 am, Michael Ossipoff wrote:
Yes, I like Duncan because burying the CW in an attempt to help your
favorite won’t help hir when it causes hir disqualification, as it probably
will.
…& Duncan is remarkably briefly-defined, needing only a very slight
modification of Black’s method.
On Fri, Oct 13, 2023 at 10:11 Forest Simmons forest.simmons21@gmail.com
wrote:
Dear EM List Friends,
We need your feedback on this draft of a proposal before we submit a
version of it to the voting reform community at large.
---------- Forwarded message ---------
From: Forest Simmons forest.simmons21@gmail.com
Date: Thu, Oct 12, 2023, 5:35 PM
Subject: Duncan Proposal Draft
To: Michael Ossipoff email9648742@gmail.com
Michael Christened our new Q&D burial resistant method "Duncan" after
Duncan Black who popularized the idea of using Borda's Method as a
fallback "completion" when the ballots fail to unambiguously reveal the
sincere "Condorcet" pairbeats-all candidate.
Our Duncan method has the same form as Black's in that the official
version directly specifies electing the unambiguous Condorcet Candidate
when there is one, and falls back to another procedure that relies on Borda
Scores, otherwise.
It should be emphasized that in both cases the fall back Borda based
expedient is rarely needed. For that reason some misguided voting reform
advocates have cavalierly opined that any decisive completion/ fallback
method would be plenty adequate to supplement the Condorcet Criterion
requirement.
However, this casual attitude ignores the feedback aspects of voting
systems in that various voting methods vary in the degree that they
encourage or discourage the creation of artificial beat cycles that
subvert/ hide the Condorcet Candidate from view, bringing the completion
method into greater prominence in a potentially unstable cycle.
Unfortunately most of the extant methods fall into this "positive"
feedback category, including Borda itself. Some less sensitive methods
like Approval and IRV/RCV have a built in "friction" that dampens the
feedback; but as systems engineers know, the high performance components
are the ones that need the addition of some carefully engineered negative
feedback "circuit" to stabilize the system as a whole.
In our Condorcet Completion context, our use of the Borda Count scores is
carefully designed with that stabilizing influence in mind: adventurous
strategists who are aware of this feature, when acting rationally will be
deterred from creating these cycles that come back to bite them. Those not
aware will find out when their ploys backfire or otherwise disappoint them.
How do these pesky cycles arise so easily in Borda and other rank based
methods?
Suppose that your personal preference schedule for the alphabetized
candidates looks like ...
A>C>X>Y>Z, and that C is the Condorcet Candidate projected to win the
election if nobody acts nefariously.
You, and like minded friends, get the idea to insincerely move your
second choice to the bottom of your ballot (so it now reads A>X>Y>Z>C) ...
not to be "nefarious" so much as to just increase the winning chances of
your favorite A.
Could this work?
Yes, under Black's method if your friends follow your lead, this "nurial"
of C under the "busses" X, Y, and Z, could easily subvert one or more of
C's pairwise victories over X,Y, and Z, into defeats of C by them, thereby
hiding C's identity of sincere Universal "pairbeater" status to just one
more member of a "beatcycle" of the form A beats X beats Y beats Z beats C
beats A.
Note that the buried candidate C still beats the buriers' favorite, A ...
because lowering C does not decrease the number of ballots that support C
over A ... which is how easily and innocently beatcycles like this can be
created in Condorcet style elections ... at least in the absence of
negative feedback from the cycle resolution fallback method.
In traditional Black that fallback method is Borda. Does that fix the
problem? ... or does it exacerbate it.
Well ... the same burial that put C at disadvantage in the pairwise
contests with X thru Z, also lowered C's Borda score by 3 counts per
ballot, and raised
the Borda score of each of X thru Z to the tune of one count per ballot.
The likely outcome is that C will end up with the lowest score, and come
in last in the finish order.
By way of contrast, under our new Duncan method, the most likely winner
is X, and the least likely winner is A, the burier faction's favorite ...
thus disappointing the burier faction supporters ... teaching them that if
they try to outsmart new Duncan with insincere ballot rankings, they are
apt to end up helping elect their third (or later) choice instead of their
first choice or their second choice ... the one that they so cleverly
buried (however innocently or without malice).
Too many dabblers in voting method reform (as well as most professionals)
are unaware of these dynamics.
But now, with your new understanding, you, at least, can become part of
the solution.
Duncan Definition:
In the vast majority of the cases ... those in which the pairwise counts
of the ballots unambiguously identify the candidate that pairbeats each of
the others ... elect that candidate.
Otherwise, elect the highest score candidate that pairbeats every
candidate with lower score.
[Nominally "score" = Borda Count, though STAR Voting scores, for example,
could also serve]
How does this Duncan fallback procedure work to prevent A from getting
elected in our scenario regarding A thru Z?
Well, could A pairbeat every lower score candidate? In particular, could
A pairbeat C, which is now at the bottom of the Borda score pile ...
certainly lower than A ...?
Well, remember that "C beats A" was the last step in the beatcycle
created by A's friends.
So A does not pairbeat every lower score candidate, and therefore cannot
win.
New Duncan is burial resistant.
Next time ... more examples and insights ...
fws