[EM] UC davis STV election data - not very useful, actually

Scott Ritchie scott at open-vote.org
Fri Nov 11 17:37:28 PST 2005

On Fri, 2005-11-11 at 18:08 -0500, Joseph Malkevitch wrote:
> Dear Scott,
> You wrote:
> > Also note that it is an NP-complete problem to figure
> > out if the election was non-monotonic from the voting data in the first
> > place.
> > 
> The way I use the term non-monotonic it refers to an election method not 
> to an election. There are in fact different variant definitions but the 
> general idea is that a system does not obey monotonicity if more support 
> for a candidate does the candidate harm in the way that the system 
> treats a candidate in two different elections. (In election 1, A wins, 
> but with more support in election 2, A loses.) Can you explain what you 
> mean by the above?

What I meant was if the election in question involved a case where
non-monotonicity has occured, IE figuring out whether the statement "If
X got his rank lowered on these ballots, X would have won!" is true for
that election.

According to this research by Bartholdi, John J. III and Orlin, James B:
- the question of figuring out if this is true is NP-Complete.

Scott Ritchie

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