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Independence of irrelevant alternatives: Difference between revisions
Independence of irrelevant alternatives (view source)
Revision as of 18:25, 18 October 2010
, 13 years agoISDA
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In [[voting system]]s, '''independence of irrelevant alternatives''' is the property some voting systems have that, if one option (X) wins the election, and a new alternative (Y) is added, only X or Y will win the election.
A less strict property is sometimes called '''local independence of irrelevant alternatives''' or '''independence of Smith-dominated alternatives''' (ISDA). It says that if one option (X) wins an election, and a new alternative (Y) is added, X will win the election if Y is not in the [[Smith set]].
All [[Condorcet method]]s fail the former criterion, but some (e.g. [[Schulze method|Schulze]]) satisfy the latter.
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