[EM] Condorcet IRV Hybrid

[Kristofer Munsterhjelm]

On 04/05/2013 09:37 PM, Forest Simmons wrote:

> The following observation about Condorcet IRV Hybrids has probably
> already been made (but I have been gone for a while):
>
> These hybrids have no good defense against burying.  For example
>
> Sincere  ballots:
>
> 40  A>C
> 35  B>C
> 25  C>A
>
> If the A faction decides to bury C, there is nothing the C faction can
> do about it unilaterally. They have to depend on the willingness of the
> B faction to elevate their compromise over favorite.

That's strange, because one of the points of James Green-Armytage in his 
voting strategy paper was that the Condorcet-IRV hybrids were 
significantly less prone to burying than ordinary Condorcet methods. 
Quoting,

"All Condorcet-efficient methods are vulnerable to burying, but this 
vulnerability seems to be substantially less frequent in the 
Condorcet-Hare hybrids than in most other Condorcet methods. The reason 
for this is that voters who prefer q to w will already have ranked q 
ahead of w, so that further burying w will not affect w's plurality 
score unless q has already been eliminated."

("Four Condorcet-Hare Hybrid Methods for Single-Winner Elections", 
http://www.econ.ucsb.edu/~armytage/hybrids.pdf, p. 8)

Or are we talking about different things? Perhaps C/IRV methods are less 
vulnerable to burying in the first place, but when they are, it's harder 
to employ defensive strategy to correct the burial?

-

Also, I seem to recall that Uncovered,X is generally more susceptible to 
burial than is X for various types of X, unless X is already rather 
susceptible to burial. It might be interesting to run a JGA type 
analysis on your "eliminate until covering" method, and compare to the 
Smith-IRV methods.