Improved Condorcet Approval: Difference between revisions

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'''Improved Condorcet Approval''' or '''ICA''' or '''tCA''' is a variant of [[Condorcet//Approval]] ~~(which is not an actual [[Condorcet method]])~~ devised by Kevin Venzke which preserves [[approval voting]]'s compliance with the [[Favorite Betrayal criterion|favorite betrayal criterion]]. It uses the [[tied at the top]] rule.

'''Improved Condorcet Approval''' or '''ICA''' or '''tCA''' is a variant of [[Condorcet//Approval]] devised by Kevin Venzke which preserves [[approval voting]]'s compliance with the [[Favorite Betrayal criterion|favorite betrayal criterion]]. It uses the [[tied at the top]] rule. Despite the name, it isn't actually a [[Condorcet method]].

==Definition==

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The definitions can only differ in practice when there are more than three candidates (unless it is allowed to approve all the candidates).

== Notes ==

As formulated, ICA fails [[Cloneproof|cloneproofness]] (though it is likely not too difficult to modify it to satisfy the criterion). Example:<blockquote>3 A

1 B1>B2>B3

1 B2>B3>B1

1 B3>B1>B2</blockquote>B1, B2, and B3 all have a pairwise defeat (they are in a cycle with each other), so A is elected for being an unbeaten candidate. But if B2 and B3 drop out:<blockquote>3 A

3 B1</blockquote>Now both A and B1 pairwise tie, and thus each has a 50% chance of winning.

==Links==