<div dir="auto">I think that if you were looking at the success rates of unilateral burial options along with the basic burial defense of truncation below sincere CW ... then the difference between Winning Votes and Margins would be more striking (still in favor of wv).</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 20, 2023, 2:12 PM Michael Ossipoff <<a href="mailto:email9648742@gmail.com">email9648742@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto">Thanks for the experiment. I hope that Tideman’s organization won’t be promoting the old margins version of RP. …unless just for maybe choosing between pizza-toppings or movies.</div><div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 20, 2023 at 07:30 Colin Champion <<a href="mailto:colin.champion@routemaster.app" target="_blank" rel="noreferrer">colin.champion@routemaster.app</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<font face="Helvetica, Arial, sans-serif">Well, I coded up
Minimax(WV) for my own evaluation. Rather to my disgust (and
contrary to Darlington) I find that it does indeed outperform
Margins for truncated sincere ballots. I ran a large number of
trials with 10001 voters under a spatial model, 8 candidates being
truncated to 4. Minimax (margins)=83.35% correct,
minimax(wv)=84.09%. Other methods which outperformed standard
minimax in the simulation include Approval Sorted Margins (in an
ordinal version suggested by Ted Stern): 84.14%; Black: 84.22%;
Smith,Borda: 84.22%. <br>
Hastily written and unreliable code, not to be trusted. <br>
CJC<br>
</font></div><div><br>
<div>On 18/09/2023 22:30, Michael Ossipoff
wrote:<br>
</div>
<blockquote type="cite">
<div dir="auto">Hi Colin—</div>
<div dir="auto"><br>
</div>
<div dir="auto">Yes, margins beats wv for social-utility under
sincere voting when there’s that vanishingly rare natural
top-cycle.</div>
<div dir="auto"><br>
</div>
<div dir="auto">But Darlington & Tideman evidently aren’t
considering resistance to offensive strategy, which is a much
bigger threat than natural top-cycles.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Protecting the CW from offensive strategy is more
important than SU in natural top-cycles.</div>
<div dir="auto"><br>
</div>
<div dir="auto">…& is better for SU.</div>
<div><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Sep 18, 2023 at
07:03 Colin Champion <<a href="mailto:colin.champion@routemaster.app" target="_blank" rel="noreferrer">colin.champion@routemaster.app</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div> <font face="Helvetica, Arial, sans-serif">Thanks to
Kevin and Michael for pointing out a feature of minimax
I was unaware of. I had however seen Richard
Darlington's paper [1] in which he referred to 'several
studies' comparing margins with winning votes. He
reports that margins 'was the big winner in all of
them'. I suppose I'll have to look deeper.<br>
Colin<br>
[1]. <a href="https://arxiv.org/abs/1807.01366" target="_blank" rel="noreferrer">https://arxiv.org/abs/1807.01366</a><br>
</font></div>
<div><br>
<div>On 18/09/2023 07:57, Michael Ossipoff wrote:<br>
</div>
<blockquote type="cite">
<div><br>
</div>
<div><br>
<div class="gmail_quote" dir="auto">
<div dir="ltr" class="gmail_attr">----------
Forwarded message ---------<br>
From: <strong class="gmail_sendername" dir="auto">Michael
Ossipoff</strong> <span dir="auto"><<a href="mailto:email9648742@gmail.com" target="_blank" rel="noreferrer">email9648742@gmail.com</a>></span><br>
Date: Sun, Sep 17, 2023 at 22:54<br>
Subject: Re: [EM] Ranked Pairs<br>
To: Forest Simmons <<a href="mailto:forest.simmons21@gmail.com" target="_blank" rel="noreferrer">forest.simmons21@gmail.com</a>><br>
</div>
<div class="gmail_quote" dir="auto"><br>
</div>
This was meant to be sent by “Reply All”, in order
to post it. So now I’m forwarding it to EM.<br>
<br>
<div dir="auto">Forest—</div>
<div dir="auto"><br>
</div>
<div dir="auto">But wv prevents truncation
(strategic or otherwise) from taking the win from
a CW.</div>
<div dir="auto"><br>
</div>
<div dir="auto">…&, with, wv, refusing to rank
anymore you don’t approve will cause offensive
order-reversal by their preferrers to backfire.</div>
<div dir="auto"><br>
</div>
<div dir="auto">I’d always take that precaution,
& would advise others to.</div>
<div dir="auto"><br>
</div>
<div dir="auto">When we discussed these guarantees
years ago they seemed absolute, & we still
have the guarantee-criteria based on them…met by
wv versions of MinMax, RP, CSSD, &
Smith//MinMax.</div>
<div dir="auto"><br>
</div>
<div dir="auto">…&, with MinMax, whose winner
can come from anywhere, not just from the
top-cycle, & so, offensive order-reversal,
when there are a fair number of candidates, is
unpredictable & risky for its perpetrators,
even if the precaution of deterrent-truncation
isn’t taken.</div>
<div><br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, Sep
17, 2023 at 21:17 Forest Simmons <<a href="mailto:forest.simmons21@gmail.com" target="_blank" rel="noreferrer">forest.simmons21@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div dir="auto">
<div><br>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On
Sat, Sep 16, 2023, 9:42 PM Michael
Ossipoff <<a href="mailto:email9648742@gmail.com" target="_blank" rel="noreferrer">email9648742@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div dir="auto">Is that RP(wv), or
RP(margins) ?</div>
<div dir="auto"><br>
</div>
<div dir="auto">RP(wv) would thwart
& deter offensive strategy, an
important property in public
elections.</div>
<div dir="auto"><br>
</div>
<div dir="auto">…&, actually, it
seems to me that MinMax(wv) would do
that better.</div>
<div dir="auto"><br>
</div>
<div dir="auto">That’s because,
choosing only from the Smith Set RP,
limits it’s choice to the strategic
top-cycle that created by the
offensive strategists.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Suppose that the CW’s
preferrers don’t do defensive
truncation (never rank anyone you
wouldn’t approve in Approval, or
whose preferrers you regard as
likely to offensively order-reverse)
?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Knowing that RP will
limit its choice to their small
strategic top-cycle, it would be
easier for the strategists to be
fairly sur that their candidate
would win in that top-cycle.</div>
<div dir="auto"><br>
</div>
<div dir="auto">But, with MinMax, the
winner is chosen more broadly, &
could be anywhere in the
candidate-set. …making it more
difficult & risky to confidently
do offensive order/reversal.</div>
<div dir="auto"><br>
</div>
<div dir="auto">RP(margins) might the
best choice for a completely honest
electorate, but MinMax(wv) seems
better for public elections, due to
its better thwarting &
deterrence of offensive strategy.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Yes, MinMax doesn’t
meet the luxury cosmetic look-good
criteria that RP meets. </div>
<div dir="auto"><br>
</div>
<div dir="auto">But for one thing, I
remind you that natural ( sincere)
top-cycles are vanishingly-rare.</div>
</blockquote>
</div>
</div>
<div dir="auto"><br>
</div>
<div dir="auto">This is the same conclusión
I have come around to. </div>
<div dir="auto"><br>
</div>
<div dir="auto">And methods that break a
three member top cycle at the weakest link
tend to reward the burier faction.</div>
</div>
<div dir="auto">
<div dir="auto">
<div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
<div dir="auto"><br>
</div>
<div dir="auto">So do you want to have
less strategy-protection, in order
for the result to maybe look better
in a vanishingly rare natural
top/cycle?</div>
<div dir="auto"><br>
</div>
<div dir="auto">…& how bad is a
violation of Condorcet-Loser anyway.
“Beaten by all the other
alternatives” sounds like some kind
of unanimity, but of course it
isn’t. It isn’t like a
Pareto-violation. I remind you that
the MinMax winner has fewer voters
preferring some particular candidate
over him than anyone else does.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Clone-Criterion
violation? How bad that really in
MinMax, especially when we’re
talking about a vanishingly rare
natural top-cycle?</div>
<div dir="auto"><br>
</div>
<div dir="auto">RP(margins) for a
completely honest electorate.</div>
<div dir="auto"><br>
</div>
<div dir="auto">MinMax(wv) for public
elections.</div>
<div dir="auto"><br>
</div>
<div dir="auto">..& about a
primary to reduce the candidates to
5: Forget the primary. If you think
people will have trouble
rank-ordering lots of candidates, I
remind you that, to vote among them
in a primary, they’d still have to
examine & choose among the
initial many candidates.</div>
<div dir="auto"><br>
</div>
<div dir="auto">…harder than ranking
only the ones you know & regard
as deserving & definitely in
your accepts& preferred set.</div>
<div dir="auto"><br>
<div class="gmail_quote" dir="auto">
<div dir="ltr" class="gmail_attr">On
Wed, Sep 13, 2023 at 00:18 Colin
Champion <<a href="mailto:colin.champion@routemaster.app" rel="noreferrer noreferrer" target="_blank">colin.champion@routemaster.app</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">I
notice that RP is the only
election method mentioned by
name in the <br>
Virginia agenda.<br>
<br>
A while ago I ran some
simulations on elections with
truncated ballots. <br>
Something I noticed was that the
presence of RP in the list of
methods <br>
made the software unacceptably
slow. I didn't look into the
cause, but <br>
there's a natural explanation,
which is the fact that RP is
known to be <br>
NP-complete when it deals
correctly with tied margins,
i.e. by <br>
exhausting over all their
permutations. Presumably if some
candidates <br>
are unpopular and ballots are
extensively truncated, then tied
margins <br>
are much likelier than with
complete ballots.<br>
<br>
I gather that practical
implementations of RP choose a
random <br>
permutation rather than
exhausting. This seems to me to
bring a danger. <br>
The presence of a few vanity
candidates (truncated off almost
all <br>
ballots) may lead to ties, and
this may lead to a comfortable
winner <br>
looking as though he owes his
victory to a coin-toss.
Obviously this <br>
undermines the legitimacy of his
win.<br>
<br>
CJC<br>
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