On Sat, 25 May 2019 at 21:33, ais...@alumni.bham.ac.uk <ais...@alumni.bham.ac.uk> wrote: > On Sat, 2019-05-25 at 21:24 +0000, James Cook wrote: > > I couldn't resist making my own attempt. It's a lot wordier than > > yours, unfortunately, but it addresses these points and omd's first > > point. Maybe there's some middle ground that's less wordy. > > > > 2. For an instant runoff decision, the vote collector determines the > > outcome by the following process. During the process, an option's > > first-place voting strength is defined to be the sum of the voting > > strengths of the ballots that list that option before all other > > options that have not been eliminated, and the remaining voting > > strength is defined to be the sum of voting strengths of valid > > ballots in this decision that list at least one option that has not > > been eliminated. > > > > a) First, all entities that are part of a valid vote, but were not a > > valid option at the end of the voting period, or are disqualified > > by the rule providing for the decision, are eliminated. > > > > b) If no ballot lists an option that hasn't been eliminated, the > > outcome is null. > > > > c) Otherwise, the vote collector successively eliminates options > > until some option's first-place voting strength is more than half > > the remaining voting strength, and that remaining option is the > > outcome of the decision. For an option to be eliminated, its first > > place voting strength must be less than or equal to the first > > place voting strengths of all other options, and if it is equal to > > another's, the vote collector must specify which option was > > eliminated in the announcement of the decision's resolution. > > There are two potential bugs in part c). One is that the vote collector > hasn't been given a mechanism to eliminate candidates (they just have > to do it, and then say what they did, but they don't have any way /to/ > do it); the other is that "For an option to be eliminated," can be > interpreted as applying to the whole process, in which case it ends up > overruling part a) due to Cretans.
Thanks. I'm now favouring Bernie's idea to use score voting, partly because it seems simpler to describe, but if others want to stick with IRV I might try addressing these bugs.