[EM] IRV vs Condorcet

Markus Schulze markus.schulze at alumni.tu-berlin.de
Thu Jul 24 08:28:40 PDT 2003

Dear Adam,

you wrote (24 July 2003):
> While winning votes-based Condorcet lacks the conventional spoiler problem,
> it is still definitely present in margins-based Condorcet.  (Markus, here's
> an example of a Condorcet supporter using a clones-type spoiler.)
> Bush 49%
> Gore 51%
> Obviously Gore wins (save the jokes).  Now add in Nader:
> Bush 49%
> Gore 24%
> Nader>Gore 27%
> This example looks pretty similar to the eye to the ABC one you used, only
> this one has the same spoiler as IRV when using margins-based Condorcet.
> Winning votes Condorcet still gives the election to Gore by a wide margin
> (sorry).

Gore and Nader are no clones in your example. They would have been clones
only when this example had looked as follows:

Bush 49%
Gore>Nader 24%
Nader>Gore 27%

Whether independence from clones is violated has nothing to do with
whether "winning votes" or "margins" are being used.

Markus Schulze

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