[EM] IRV and Brown vs. Smallwood

[Kristofer Munsterhjelm]

Don & Cathy Hoffard wrote:

> IRV elections are LESS subject of strategic voting than a primary and a
> top-two run-off.
> Both voting systems are clearly monotonic.

Are you saying that both top-two runoff and IRV is monotonic? There are 
lots of examples as to how IRV is nonmonotonic - Yee diagrams also show 
that it's not a rare occurence.

As for top-two runoff, I suppose that depends on how you interpret it. 
If you say that TTR is equal to a system where the voters first vote for 
whoever they placed first (in the first round), then for which of the 
two remaining that they ranked highest (in the second round), then with 
three candidates, TTR is equal to IRV and so is nonmonotonic. However, 
this is probably not what voters do, since they move their votes around, 
but since monotonicity is a property of single-ballot systems, that 
muddles the picture.

> Why is Monotonicity an issue, if they are both systems are monotonic and
> monotonic is not ever a constitution requirement.

Monotonicity is an issue because it degrades the result. Now, you might 
say that many problems degrade the result (Consistency, Participation, 
etc), but many of those are very hard to satisfy; monotonicity is not, 
unless you want both LNHelp and LNHarm (like IRV).