Kevin Venzke stepjak at yahoo.fr
Wed Sep 21 06:01:23 PDT 2005


--- Jobst Heitzig <heitzig-j at web.de> a écrit :
> You wrote:
> > FBC. That's the important one for public political elections. But SFC
> > would be good too, and also the other majority defensive strategy
> > criteria--GSFC, WDSC, & SDSC.
> I'm not a particular expert in these criteria. Forest is discussing FBC
> and DMC in detail in some of his recent posts. As for some of the
> others, could it be true that they follow from the following fact about
> DMC: When a majority prefers X to Y, and rank X above Y, and place their
> approval cutoff between X and Y, then Y is doubly defeated by X and thus
> Y cannot win.

SDSC follows from this, and WDSC follows from SDSC.

I don't believe DMC satisfies SFC:

49 A
24 B>A
27 C>B

It's possible to place the DMC approval cutoffs so that B has the lowest
approval, and A wins.

I believe this would be a violation of SFC, since more than half of the
voters prefer B to A, but no majority prefers anyone to B. That is, B is
clearly preferred to A, and no one is clearly preferred to B.

I'd say the purpose of SFC is to protect the B>A voters from giving the
election to A. (That's assuming B wins and not C.)

Kevin Venzke


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