[EM] Best Deterministic Ranked Preference Method?

Kevin Venzke stepjak at yahoo.fr
Fri Dec 25 10:28:06 PST 2020

Hi Forest,

Real quick:

Le vendredi 25 décembre 2020 à 00:15:20 UTC−6, Forest Simmons <fsimmons at pcc.edu> a écrit : 
>> (One could suggest that the approval cutoff be placed prior to the rank that exceeds 50% of the random ballot odds, 
>> but this doesn't seem workable because it means a majority favorite can't receive his votes.)
>> Here's a Weinstein mono-raise example for your consideration.
>> 0.311: D>C>A>B approves DCA
>But .311+ .186 +.270 > .50 so only D & C can be approved. "the total probability of approved alternatives on a ballot 
>cannot exceed 50 percent" 

I considered that initially. But what about majority favorites? They wouldn't receive any of their top rankings as approval.

>> D wins. Now change the 0.143 bloc to vote D>B at the top instead of B>D. 
>In my version this transposition is actually two moves because equal ranking must be allowed for random ballot 
>probabilities to split (between B and D in this case). So raising D leads to B=D, and it takes another move to lower B.

I could see permitting a method that allows ER to perform the transition in two steps. However, for Mono-raise, two steps is strictly a harder test. If you change the winner taking a single step, you will still change the winner when taking two steps to get to the same place.


More information about the Election-Methods mailing list