Dear Alex, you wrote (7 Jan 2003): > The situations giving rise to ties can be derived from a symmetry > principle (without definitions I don't know whether your criteria > amount to the same): If candidate A wins, and all voters then > interchange candidates A and B in their rankings, candidate B should > win. If candidate C wins, and all voters then interchange candidates > A and B in their rankings, candidate C should still win.
This "symmetry principle" is usually called "neutrality". "Anonymity" means that swapping voters should not change the result of the elections. However, consider the following example: 40 voters vote A > B > C > D > E. 40 voters vote B > C > D > A > E. 40 voters vote C > A > D > E > B. Although this is not a symmetric situation, the used election method must violate Neutrality or Anonymity or Decisiveness or Local Independence from Irrelevant Alternatives in this example. Markus Schulze ---- For more information about this list (subscribe, unsubscribe, FAQ, etc), please see http://www.eskimo.com/~robla/em
