[EM] Hybrid/generalized ranked/approval ballots

[Kevin Venzke]

Hi Peter,
 
We consider rank ballots that allow equality of ranking and truncation all
the time.

For Condorcet methods the question of how to treat equality of ranking is
what Juho and I usually talk about.

If Markus prefers not to use the split vote treatment it is probably
because it violates CDTT (it doesn't respect voted majorities) and
the Plurality criterion:

35 A>B
25 B
40 C

A will win. This is only acceptable when you assume that the B and C
voters meant to say that A is just as good as the other candidate that
they didn't rank. I don't think this is likely to be what voters expect.
It seems misleading to even allow truncation as an option if it's treated
like this.

There's also a strategy issue. When truncation is counted as zero votes,
then you have three options when you decide how to rank the worse of
two frontrunners (who is really better than all the other unimportant
candidates):
1. sincerely support the worse frontrunner
2. insincerely bury the worse frontrunner (which can steal the election
if the other faction does #1, or else elect a completely terrible
candidate if the other faction does #2 or #3)
3. truncate. That protects the better frontrunner and it is not trying
to steal the election.

When you can't meaningfully truncate, you don't have #3. So #2 is both
your offensive and your defensive strategy. That seems like a problem to
me.

Kevin Venzke