[EM] "Unmanipulable Majority" strategy criterion

[Chris Benham]

Kristofer,
Thanks for at least responding.

"...I won't say anything about the desirability because I  don't know what it implies;.."

Only judging criteria by how they fit in with other criteria is obviously circular. 

Do you (or anyone) think that judged in isolation this strategy criterion is desirable?

It is true that some desirable/interesting criteria are so "restrictive" (as you put it) that
IMO  compliance with them can only be a redeeming feature of  a method that isn't
one of the best.  (I  put Participation in that category.)

Maybe some people would like me to paraphrase this suggested criterion in language 
that is more EM-typical:

'If candidate A majority-strength pairwise beats candidate B, then it must not be possible for B's 
supporters (pairwise versus A) to use Burial or Pushover strategy to change the winner from A
to B.'

"Destructive burial would be trying to make X not win,..."

Your "destructive burial"  looks  almost synonymous with *monotonicity*.

Chris Benham
 
 
Kristofer Munsterhjelm wrote (Thurs.Nov.27:
Chris Benham wrote:
> I have a suggestion for a new strategy criterion I might call 
> "Unmanipulable Majority".
>  
> *If (assuming there are more than two candidates) the ballot
> rules don't constrain voters to expressing fewer than three
> preference-levels, and A wins being voted above B on more
> than half the ballots, then it must not be possible to make B
> the winner by altering any of the ballots on which B is voted
> above A.*
> Does anyone else think that this is highly desirable?
>  
> Is it new?

I think it's new. I won't say anything about the desirability because I 
don't know what it implies; it could be too restrictive (like 
Consistency) for all I know.

It would be possible to extend this to a set. For instance: "if the 
method elects from a set w, then it must not be possible to make a 
candidate X outside w the winner by modifying ballots on which X is 
ranked above all in w".

Or a more general case, with constructive and destructive burial. 
Constructive burial would be trying to make Y win instead of X. 
Destructive burial would be trying to make X not win, though in that 
case you would have to consider what kind of ballots could be changed, 
since there's no equivalent of B in the destructive burial case. 
Destructive burial also sounds too strict, that no useful method could 
fulfill it (unless only very specific ballots were permitted to be 
changed, e.g those who rank X last).



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