Thanks for the input, very helpful. More comments below:
On Jan 27, 2004, at 7:29 PM, Dave Ketchum wrote:
I like what Ernest writes, though I see a bit of room for improvement and suggest "tournament" as a less foreign-sounding title (even though its ancestry is also French).
Hmm, maybe. It is better than Condorcet, but to me tournament evokes an image of knights jousting on horses.
Someone (sorry, I forgot who) suggested the word Pairwise is important. I could live with the name Pairwise Matchup Voting (PMV). Pairwise by itself seems too vague, somehow
Yeah, my friends (on the radical centrist list) are unanimous that the term Condorcet has to go. :-)
I have been proposing the term 'Instant Matchup Voting', or IMV, by analogy with Instant Runoff Voting. I compare it to a round-robin tournament, which most people have direct experience with. I think this leads to a simple, easy to visualize definition:
Ahead of much that I have seen, but I suggest tournament as even easier to visualize from. My definition will follow yours.
Well, tournament does have the idea of a series of matches, but not necessarily individual pairwise matchups, I don't think. We could use the term Instant Round-Robin, which is much more explicit, but IRR is too close to IRV. :-(
IMV:
1. Each rank-ordered ballot is interpreted as a series of "Instant Matchups"Tournament:
That is A > B > C, implies one point each for the three pairwise Matchups A > B, B > C, and A > C
Note that "A>B" is counted separately from "B>A" (i.e., winning votes)
2. Tally up the N * (N-1) Matchups, for each ordered pair of candidates
3. If one candidate beats everyone, that's the absolute winner
4. If there is a 'rock-paper-scissors' tie (A >= B, B >= C, C >= A),
the tiebreaking winner is the candidate from that group with the 'least greatest defeat'
0. Voters simply rank as many of the candidates as they choose, starting with their most-preferred.
1. Each rank-ordered ballot is interpreted as a series of matches among all
candidates in the election:
That is, ranking A > B > C, and D and E not ranked by this voter,
implies each ranked candidate winning over each candidate ranked later, and
over each unranked candidate.
Thus unranked candidates do not get counted as ranked over each other.
That's a good point. I don't think we usually spend enough time explaining how the ranking is supposed to work, so it would be good to be more explicit.
Note that "A>B" is counted separately from "B>A" (i.e., winning votes).
2. Tally up the number of wins for each ordered pair of candidates in an
N*N array (with an empty diagonal, for candidates do not play against themselves).
Good point, N*N does reduce explanation.
3. If one candidate wins when compared with each other candidate, that's
the absolute winner.
4. If no absolute winner, we have a 'rock-paper-scissors' near tie such as
(A >= B, B >= C, C >= A), and the tiebreaking winner is the candidate from
that group with the 'least greatest defeat'.
NOTE: I consider 'least greatest defeat' unacceptably opaque for this purpose, and ask for help in providing simpler words.
Fair enough. How about "whose worst loss is the smallest"? Or simply "lost by the smallest margin" (a little ambiguous, but sounds simpler) - can always go into more detail elsewhere.
BTW: Debatable whether voters should be permitted to rank candidates as equal.
Is there any good reason not to? Implicit equal ranking certainly makes it clearer about how unlisted candidates are counted. Any if at all possible, it seems good to give people the option of equality rather than forcing a random choice. Has anyone presented a clear argument for or against equal ranking?
If so then, for each pair of equal candidates, count 1/2 win for each (thus if two voters rank A=B=C then A>B, B>A, A>C, C>A, B>C, and C>B each get credited one full win).
That doesn't make any sense to me. If two candidates are ranked, I think that neither should get the win -- at least if we're doing winning votes (wv) For example, if all the candidates that most people don't rank at the bottom of the list get a win against each other, then one single vote in favor could make that person the 'wv' winner! Right?
Any more thoughts on the implications of Smith PC on strategy, assuming we can hammer out a decent, simple explanation?
-- Ernie P.
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