[EM] [Condorcet] Re: IRV vs Condorcet

[Jameson Quinn]

> now ask yourself the question whether or not Condorcet satisfies these
> criteria (assuming a CW exists).
>
>
>
Of course it does, because you only included the anti-strategy criteria
which it does pass. But what do you call this:

Hypothetical true preferences:
39.4: D>H=C
30.8: H>C>D
27.6: C>H>D
2.5: NOTA

H is the condorcet winner. But if just 8% from the C voters instead vote
C>H=D (or 4% of them vote C>D>H, if equal rankings aren't allowed), then
there is no Condorcet winner, and C could win.

(This election actually happened recently in Hawaii, although of course the
lower preferences are simplified guesses).

My APV proposal does very well on this and other scenarios. Specifically,
for this scenario, the pure strategy which is closest to being a
trembling-hand equilibrium is the "good" situation where H wins in one round
(Not true of Approval, Bucklin, margins Condorcet, Range; IRV is the only
"major" system I know of which passes this test). And it is monotonic, and,
unlike IRV, unilkely to fail to find a centrist Condorcet winner.

In fact, I can't think of a single scenario where the pure strategy closest
to being trembling-hand equilibrium doesn't give an very-arguably "right"
answer in one round for APV. And I can easily get IRV to give the wrong
answer, so APV is the only system I know of which pass this test.

JQ
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