[Election-Methods] Challenge: Elect the compromise when there're only 2 factions

[Dave Ketchum]

On  Wed, 22 Aug 2007 09:28:24 -0300 Diego Renato wrote:
> 2007/8/22, Jobst Heitzig <heitzig-j at web.de <mailto:heitzig-j at web.de>>:
> 
>     A common situation: 2 factions & 1 good compromise.
> 
>     The goal: Make sure the compromise wins.
> 
>     The problem: One of the 2 factions has a majority.
> 
>     A concrete example: true ratings are
>        55 voters: A 100, C 80, B 0
>        45 voters: B 100, C 80, A 0
> 
>     THE CHALLENGE: FIND A METHOD THAT WILL ELECT THE COMPROMISE (C)!
> 
>     The fine-print: voters are selfish and will vote strategically...
> 
>     Good luck & have fun :-)
> 
>  
> Since A has a majority, no method is guaranteed to elect C. If both A 
> and B voters are not sure which faction is larger, it is possible vote 
> for their preferred candidate and C under approval voting, or put C 
> highly rated under range voting, and C be elected.

Diego lists both:
      Approval - at least 56 A and B voters also approving C - reducible 
by some giving up on approving A or B.
      Range - similar adjustment via ratings.
NOT MENTIONED - Condorcet:
      46 A voters ranking C at top, without any giving up on the A vs B 
competition - reducible by B voters cooperating in this.
> 
> ________________________________
> Diego Santos
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  Dave Ketchum   108 Halstead Ave, Owego, NY  13827-1708   607-687-5026
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