[EM] [ER] FBC-complying Margins-like method (?)

[Kevin Venzke]

Chris,

--- Chris Benham <chrisbenham at bigpond.com> a écrit :
> Kevin, Warren, other FBC freaks,
> 
> I've recently had an idea for a FBC-complying  Margins method.
> 
> "Voters rank the candidates, equal-ranking and truncation allowed.
> (1) Make  pairwise comparisons. Treating pairwise defeats by margins 
> that are smaller
>  than or equal to the number of ballots on which both candidates are 
> ranked equal-top
> as pairwise equalities,  eliminate candidates that are not in the 
> smallest non-empty set of 
> candidates that are pairwise undefeated by any outside-the-set
> candidates.
> 
> (2)If  more than one candidate remains, drop eliminated candidates from 
> the ballots and
> then delete ballots that make no ranking distinction between remaining 
> candidates, and repeat
> step 1.

There are two reasons why I don't believe this can work.

1. You're using a beatpath concept. Although you're replacing certain
wins with pairwise ties, it could be that a pairwise tie between X and
Y is what causes them to be excluded from the top tier. Replacing wins
with ties only helps to satisfy FBC when it's clear that a tie between
X and Y is at least as good for them as one of them beating the other.

2. You're eliminating candidates and recalculating. I think all you
can afford to do is disqualify candidates without recalculating anything.
Elimination makes it difficult to foresee what a specific vote is capable 
of doing across multiple rounds. It's much the same issue as Raynaud
or Nanson failing monotonicity.

Kevin Venzke



	

	
		
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