Distributed Score Voting: Difference between revisions
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Aldo Tragni (talk | contribs) No edit summary |
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Graphically, each candidate is a node; the head-to-head is represented by an arrow, leaving the winning candidate, entering the losing candidate. The tie is represented as a double arrow entering, that is both candidates are considered losers. |
Graphically, each candidate is a node; the head-to-head is represented by an arrow, leaving the winning candidate, entering the losing candidate. The tie is represented as a double arrow entering, that is both candidates are considered losers. |
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2) Find the smallest set X of nodes that don’t have incoming arrows, coming from outside the set. |
2) Find the smallest set X (Smith set) of nodes that don’t have incoming arrows, coming from outside the set. |
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Then remove all candidates not in X from the votes. |
Then remove all candidates not in X from the votes. |
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6) If you want to know the % of victory of the winning candidates then, in each original vote, you must remove all the candidates who haven’t won, and normalize* the vote with the formula used in point 3 (with W=100 fixed). The sum of points for each candidate will indicate the % of victory. |
6) If you want to know the % of victory of the winning candidates then, in each original vote, you must remove all the candidates who haven’t won, and normalize* the vote with the formula used in point 3 (with W=100 fixed). The sum of points for each candidate will indicate the % of victory. |
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===Head-to-head=== |
===Head-to-head=== |
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In a head-to-head between candidates A and B, a vote like A[10], B[30], C[60], D[0] could be treated in 2 different forms: |
In a head-to-head between candidates A and B, a vote like A[10], B[30], C[60], D[0] could be treated in 2 different forms: |
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To make the writing of the vote more comprehensible and simple, the voter can be left with almost complete freedom in the use of numerical values or only X. |
To make the writing of the vote more comprehensible and simple, the voter can be left with almost complete freedom in the use of numerical values or only X. |
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Before the counting process, the |
Before the counting process, the votes will be normalized to 100-point votes, where the Xs are considered as equal weight values. |
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Examples of how a vote can be written by the voter and subsequently, in the counting, converted into 100 points: |
Examples of how a vote can be written by the voter and subsequently, in the counting, converted into 100 points: |
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The complexity in writing the vote adapts to the voter, and it’s also noted that, if 101 or 99 points are mistakenly distributed, the vote will still be valid. |
The complexity in writing the vote adapts to the voter, and it’s also noted that, if 101 or 99 points are mistakenly distributed, the vote will still be valid. |
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==Criteria== |
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Criteria met by DSV: |
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* Majority criterion |
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* Majority loser criterion |
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* Mutual majority criterion |
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* Condorcet criterion |
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* Condorcet loser criterion |
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* Smith criterion |
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* Independence of irrelevant alternatives |
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* Independence of clones criterion |
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* Monotonicity criterion |
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* Reversal symmetry |
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* Pareto criterion |
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Criteria not met by DSV: |
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* Participation criterion |
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* Consistency criterion |
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* Later-no-harm criterion |
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* Later-no-help criterion |
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* Favorite betrayal criterion |
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The first two criteria not met are derived mainly from the fact that DSV wants to ensure the victory of the candidate who wins all the head-to-head (when it exists). |
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The last 3 unmet criteria can instead generate tactical votes, described below. |
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===Tactical votes=== |
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In an election, the results of the head-to-head are the following: A>B , B>C , C>D , D>A , A>C , D>B and in the end wins B. |
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A voter who in this case supported the candidates as follows: A>D>B>C he could change his vote as follows: A>D>C>B to favor C more than B (without disadvantaging A and D). |
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This tactical vote could cause B to lose head-to-head between B and C and in this case B would be the candidate who loses all head-to-head, being eliminated immediately. The winner would no longer be B. |
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This type of tactical vote works only if: |
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* there is a condorcet paradox which includes at least 4 candidates. |
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* through the tactical vote, the candidate who should have been the winner can be taken out of the Smith set. |
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* the new winner is actually a better candidate than the previous one (the new winner in the example could also be C). |
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* the voter has a fairly precise knowledge of the likely ballots result, without which this tactical vote would turn against him. |