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Re: Dec 15 voting amendment draft



I believe most efficient way to get an effective election method it to build up a set of essential criteria, and select a method that matches those criteria. I found the criteria mentioned on electionmethods.org too vague for me to understand, due to the use of the words 'sincerly' and 'not falsifying'. So I've attempted to translate the criteria below.

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Monotonicity Criteria.

If
(i) There is an election X in which option A wins,
(ii) There is a vote V that ranks option B above option A.
(iii) There is an election Y which is identical to election X except that vote V has option A and option B swaped on their preference list.
then
Option A must win election Y.

Smith Criteria.

If
(i) There is a non-empty set of options S.
(ii) Every option in S superdefeats every option not in S.
(iii) The election is not effected by quorum defaults.
then
The winner must be a option in the set S.

Also, another criteria.

Participation Monotonicity.

If
(i) There is an election X in which option A wins.
(ii) There is a vote V ranks option A over option B.
(iii) There is an election Y identical to election X except that it has an additional vote V.
then
Option B must not win election Y.

What Participation Monotonicity says is, that participation will never cause a less prefered option to win than non-participation. That is, it is never advantagous to not participate.

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Argument that feb 7th draft method is not acceptable.

Axiom: For an election system to be acceptable, it must follow Participation Monotonicity.

Therefore, for feburary 7th draft to be acceptable, it must follow Participation Monotonicity.

(i) Let election X =

2 ABD
1 BDA

(D is default, A has 1:1 supermajority, B has 1:1 supermajority)

Option A wins election X.

(ii) Let vote V = DAB

Vote V ranks option A above option B.

(iii) Let election Y =

2 ABD
1 BDA
1 DAB

(D is default, A has 1:1 supermajority, B has 1:1 supermajority)

Which is identical to election X except vote V is added.

Then for feb 7th draft to follow Participation Monotonicity, option B must not win election Y.
However, option B does win election Y.

Therefore, feb 7th draft does not follow Participation Monotoncity.

Therefore, feb 7th draft is not acceptable.

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One thing I have assumed is true above is that Participation Monotoncity is essential. In my opinion the concensus on this mailing list is that the election method should not encourage and reward anyone for not voting, and hence Participation Monotoncity is essential. If anyone disagrees with that, or my argument is flawed at some point, please say.

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Clinton Mead



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