[EM] RE : Kevin, SFC

[Kevin Venzke]

Hi,

--- Michael Ossipoff <mikeo2106 at msn.com> a écrit :
> Kevin said:
> 
> Hi, By the way, you can also ensure a method satisfies SFC by having it 
> comply with this votes-only criterion: "If more than half of the voters
> rank 
> A over B, but there is no majority of the voters ranking some third 
> candidate over A, then B doesn't win."
> 
> I reply:
> 
> First, does Kevin’s criterion apply only to rank methods? My criteria
> apply  to all methods.

I wrote the above to help clarify the implications of SFC on at least
rank ballot methods.

I won't get into again how I interpret criteria so that they apply to
all methods, since it wasn't my point to suggest an alternative to SFC.

> Kevin continues:
> 
> Personally I feel that SFC *is* more about avoiding an embarrassing
> result, than about providing a strategy guarantee
> 
> I reply:
> 
> Kevin can personally feel anything that he wants to. And if he chooses to
> not tell us why he personally feels it, that’s fine too. It’s pretty
> obvious 
> that SFC provides a strategy guarantee: The majority that it refers to
> can 
> defeat whomever they like less than the CW, by doing nothing more than 
> voting sincerely, and without knowing who the CW is, as long as no one 
> falsifies.

I've told you why in the past actually. I don't think it is a very 
*useful* guarantee, since you can't know in advance whether you qualify 
for it, and if you did know that you qualify for it, you'd also know that
you don't need to use it, since your candidate should win no matter what
you do with your lower rankings.

I consider SDSC more of a strategy guarantee since you can guess that it
will protect you, at least when there are two major frontrunners and
you don't want to jeopardize the better of the two.

> However, if a failure to meet SFC would embarrass Kevin, then I laud
> Kevin’s aesthetic taste.

Thanks.

> Kevin continues:
> 
> ... --- Michael Ossipoff <mikeo2106 at msn.com> a écrit : > SFC is more 
> demanding than the Condorcet Criterion. Hm, I don't think I would say 
> that... You can satisfy one and not the other. And I can think of a
> couple of criteria compatible with SFC but not Condorcet.
> 
> I reply:
> 
> It’s probably ultimately a subjective individual opinion, which criterion
> is 
> more demanding. But SFC must be more difficult to meet, since all 
> pair-wise-count methods meet CC, but only the wv Condorcet methods meet
> SFC.
> 
> Is there a method that meets SFC but fails CC? There are certainly
> methods that meet CC but fail SFC.
> 
> Maybe Kevin and I have different meanings for criterion demanding-ness.

Well, the way I understand CC and "pairwise count method," MMPO and
MDDA are pairwise count methods that satisfy SFC but fail CC.

I think SFC and CC are similarly demanding in that they're both hard to
satisfy without regarding pairwise comparisons. From there I guess it
is subjective. CC requires the method to consider most or all of the
pairwise comparisons, while SFC needs to be sensitive to defeats of
certain strength (at least as far as I've so far found).

Kevin Venzke


	

	
		
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