[Election-Methods] Unnecessary voting method? (was: How to use rankings below approval cut-off)

[Steve Eppley]

Hi,

Assuming I'm correctly understanding a voting method Stéphane Rouillon 
used in a recent message (excerpted below), which he called "Repetitive 
Condorcet (Ranked Pairs(Winning Votes)) elimination," it is 
unnecessarily complicated because it chooses the same winner as Ranked 
Pairs(Winning Votes), which of course is simpler. 

Ranked Pairs(Winning Votes), also known as MAM, satisfies H Peyton 
Young's criterion Local Independence of Irrelevant Alternatives (LIIA).  
One implication of LIIA is that elimination of the last-ranked 
candidate(s) does not change the ranking of the remaining candidates.

By the way, a different criterion has been masquerading as LIIA in 
Wikipedia.  Peyton Young defined the real LIIA in his 1994 book Equity 
In Theory And Practice (if not earlier).

--Steve
--------------------------------------
Stéphane Rouillon wrote:
-snip-
> Let's try a counter-example:
>
> 3 candidates A, B, C and 100 voters.
> Ballots:
> 35: A > B > C
> 33: B > C > A
> 32: C > A > B
>
> Repetitive Condorcet (Ranked Pairs(winning votes)  ) elimination would 
> produce
>
> at round 1:
> 68: B > C
> 67: A > B
> Thus ranking A > B > C
> C is eliminated.
>
> at round 2:
> 67: A > B is the ranking
> B is eliminated
>
> at round 3:
> A wins.
-snip-