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

[Dave Ketchum]

-------- Original Message --------
Got lost?
Date: Wed, 22 Aug 2007 14:32:55 -0400

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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