[EM] new working paper: "Four Condorcet-Hare hybrid methods for single-winner elections"

[Kristofer Munsterhjelm]

Kevin Venzke wrote:
> Hi Kristofer,
> 
> --- En date de : Sam 19.2.11, Kristofer Munsterhjelm <km-elmet at broadpark.no> a écrit :
>> Some other observations: it seems that adding a Smith
>> constraint (Smith, or Smith//) limits the vulnerability to
>> compromising, and that having the base method satisfy LNHarm
>> greatly limits vulnerability to burial, since the base
>> method is then immune to burial.
> 
> Well actually it's LNHelp that gives you immunity to burial. (DSC, QR, and
> MMPO are vulnerable in varying ways.) And sadly it seems to me that the 
> desirability of having other voters doubt that you will express a certain
> lower preference, mitigates the advantage of LNHarm.
> 
> If you look at LNHelp instead you will probably start out with 
> Condorcet//Approval, which actually is one of my favorite methods due to
> anti-burial properties. Maybe DAC is of interest too.

If that's the case, then LNH isn't enough. See Armytage's strategy 
paper, http://www.econ.ucsb.edu/~armytage/svn2010.pdf . In it, Bucklin 
is shown to be vulnerable to burial (e.g. page 28). This is quite 
strange because Bucklin isn't Condorcet-efficient and so could (and 
does) meet LNHelp outright.

It also seems possible to bury using Bucklin. Say that your sincere 
preference is A > B > C > D, and that B wins in the second round, but if 
you could somehow keep B from winning, then A would win in the third. 
Then dishonestly burying B, say by voting A > C > D > B, would help.

A method that passes LNHarm doesn't have this problem, AFAIK, because 
later preferences cannot harm your earlier preferences. Your chance of 
having A win is the same whether you vote A > B > C > D or A > D > C > B.