[EM] Mono-switch-plump criterion

[Kevin Venzke]

Hi Chris,




>----- Mail original -----
>De : C.Benham <cbenham at adam.com.au>
>>  Mono-switch-plump:
>>
>> *The probability of candidate X winning must not be reduced if one or 
>> more ballots that
>> plump for any not-X  are replaced by an equal number of ballots that 
>> plump for X.*
>
>Previously I showed that this is failed by the following methods:
>
>Schulze (aka Beatpath), Ranked Pairs, River, MinMax (all equivalent with 
>3 candidates) if they use Winning Votes to weigh pairwise defeats.
>

I'd say Schulze, RP, and River can't satisfy it in any case, since X's
election might depend on tracing a win through a victory of non-X over

some third candidate. Then when non-X loses some ballots, he can lose that

victory, making X lose.


Any kind of path tracing is likely to be an obstacle.

Kevin