Chris and Mike, I think I finally have the right version which I will call MSAC for Majority Support Acquiescing Coalitions:
Definitions: A coalition is a subset of the candidates. A ballot acquiesces to a coalition of candidates iff it rates no candidate outside the coalition higher than any member of the coalition. A Majority Support Acquiescing Coalition is a coalition that is acquiesced to by more than half of the ballots. A Majority Support Acquiescing Coalition is minimal if it ceases to be a Majority Support Acquiescing Coalition when any one of its members is removed. Method Definition for MSAC: (1) First find all of the Minimal Majority Support Acquiescing Coalition. (2) Among these call the one with the greatest support G. (3) Elect the member of G with the greatest average rating. ----- Original Message ----- From: "C.Benham" Date: Tuesday, December 13, 2011 11:19 am Subject: Forest: MAMT To: em > Mike, > > I can see how MAMT tries to meet Mono-add-Plump, but it fails. > > 49: C > 27: A>B > 24: B>A > > MAMT (like all reasonable methods) elects A, MSAC also elects A. >But say we add 20 > ballots > that plump for A. > > 49: C > 27: A>B > 24: B>A > 20: A (new ballots) > > (120 ballots, majority threshold 61). > > Now there are two "minimal subset" acquiescing majorities: {AB} > 71 and > {CA}69. All three candidates are qualified so the most top-rated > candidate (C) wins. But under MSAC candidate A still wins, because the {A, B} coalition is the set G, and the range winner of this set is A. Note also that the MSAC winner is C for the following set of ballots: 49: C 27: A>B 24: B , because in this case the coalition {B, C} is the value of G, and C is the range winner of this coalition. Forest ---- Election-Methods mailing list - see http://electorama.com/em for list info