SODA voting (Simple Optionally-Delegated Approval): Difference between revisions
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In general, this system, because it provides perfect information on voting totals at the time when delegation is happening, will make strategy obvious. (The pairwise champion/Condorcet winner is a strong Nash equilibrium; and even if there are 3 or 4 candidates in the Smith set, there is still a unique Coalition Proof Nash Equilibrium). This has the paradoxical result that, as long as few voters disagree with their favored candidate's ordering (or as long as there are minor "delegator-only" candidates for every preference ordering of the majors which is held by a significant number of voters), this system will in practice be '''more Condorcet compliant than a Condorcet method''' (because strategy could confound a true Condorcet method, but delegation strategy in SODA is strongly attracted by a correct equilibrium). |
In general, this system, because it provides perfect information on voting totals at the time when delegation is happening, will make strategy obvious. (The pairwise champion/Condorcet winner is a strong Nash equilibrium; and even if there are 3 or 4 candidates in the Smith set, there is still a unique Coalition Proof Nash Equilibrium). This has the paradoxical result that, as long as few voters disagree with their favored candidate's ordering (or as long as there are minor "delegator-only" candidates for every preference ordering of the majors which is held by a significant number of voters), this system will in practice be '''more Condorcet compliant than a Condorcet method''' (because strategy could confound a true Condorcet method, but delegation strategy in SODA is strongly attracted by a correct equilibrium). |
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== Technical |
== Technical note == |
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How can spoilers still be possible under SODA if the CW has a known, strong equilibrium in their favor? Because it is not necessarily unique. Imagine two, similar candidates in a natural majority coalition, running against one slightly-minority candidate. One of the two majority candidates is almost certain to be the CW, but if the other similar candidate can make a credible threat to withold aproval, and the CW would rather cede to this blackmail than see the minority candidate win, then the non-CW also has a (smaller) strong equilibrium in their favor. |
How can spoilers still be possible under SODA if the CW has a known, strong equilibrium in their favor? Because it is not necessarily unique. Imagine two, similar candidates in a natural majority coalition, running against one slightly-minority candidate. One of the two majority candidates is almost certain to be the CW, but if the other similar candidate can make a credible threat to withold aproval, and the CW would rather cede to this blackmail than see the minority candidate win, then the non-CW also has a (smaller) strong equilibrium in their favor. |
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