[EM] Quick and Clean Burial Resistant Smith, compromise

[Daniel Carrera]

On Sat, Jan 8, 2022 at 6:20 PM Kristofer Munsterhjelm <km_elmet at t-online.de>
wrote:

> > Is there an intuitive explanation why Smith-IRV and Benham are more
> > resistant to strategy? I'm trying to find Behman's method on the
> > electowiki but I'm not finding it. I was sure I had seen it there
> > before. Does it have an alternate name?
>
> Perhaps you misspelled it - it isn't Behman but Benham. You should be
> able to find it at https://electowiki.org/wiki/Benham's_method :-)
>
> As for why the Condorcet-IRV methods resist strategy better, I think
> it's a combination of dominant mutual third burial resistance (which
> also renders the method immune to the DH3 scenario) and chicken dilemma
> resistance.
>
> An example of the three categories can be seen on the left in
> https://www.votingmatters.org.uk/ISSUE29/I29P1.pdf, on page 8. Borda is
> in the top category, minmax is well, in minmax, and IRV and the
> Condorcet-IRV hybrid (Woodall) are at the bottom.
>

Thanks! I've read the paper. This is really interesting. I tried to write a
program to reproduce the experiment so I could add other Condorcet-IRV
methods (IRV-BTR and Raynaud(Gross Loser)) but I got stuck. I couldn't
figure out how to implement the coalition of strategic voters. The paper
doesn't really explain how it's done. It says:

"In order to avoid massive computational
cost, I make the restrictive assumption that all
voters in the strategic coalition must cast the
same ballot"

I couldn't figure out how to decide which voters need to be in the
coalition or what ballot they need to cast to maximize their chances.

In any event, I was also interested in that big table that shows the
features of the systems (MAP/MA, ISDA, etc). I would love to see a table
like that for Condorcet systems. Something like the one on Wikipedia, but
more granular. For example, I saw on the electowiki that IRV-BTR and
Raynaud pass ISDA, but it wasn't clear whether Raynaud(Gross Loser). In the
paper, the methods that pass ISDA (Smith-AV and Tideman) also
fail mono-add-plump and mono-append and I'm wondering if that's always
true, or if it's just incidental.



> Unfortunately, pretty much every method in the resistant category is
> nonmonotone. fpA-fpC (which Kevin calls my Linear method) is monotone
> and passes both DMTBR and chicken resistance, but I don't know how to
> extend it to a Smith set of more than three candidates.


I'm not familiar with fpA-fpC. Is that in the wiki somewhere?


-- 
Dr. Daniel Carrera
Postdoctoral Research Associate
Iowa State University
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