[EM] compromising strategy in Condorcet...

[James Green-Armytage]

Okay, excellent! Now let's see if we can build on this. Here's what I'd
like to know: Are there any situations in IRV where there is NO Condorcet
winner, and yet compromising is NOT a useful strategy? That is, does the
absence of a Condorcet winner mean that some group of voters can
potentially benefit from compromising in IRV? If so, then we would have
logical proof that compromising strategy incentive is more frequent in IRV
than Condorcet. Or, is there any other easy way to prove that IRV has a
more frequent compromising strategy? Does every example which produces a
compromising incentive in Condorcet also produce a compromising incentive
in IRV? I think that this is a key point of comparison between the two
methods. 

my best,
James

Markus Schulze <markus.schulze at alumni.tu-berlin.de> writes:
>Dear James Green-Armytage,
>compromising is a useful strategy only when there is
>no Condorcet winner.
>Suppose candidate A is the Condorcet winner according to
>d_sincere. Then ranking the candidate B insincerely high
>to make him win is a useful strategy only for those voters
>who strictly prefer candidate B to candidate A. However,
>in so far as d_sincere[A,B] > d_sincere[B,A], candidate A
>is still the Condorcet winner when all those who strictly
>prefer candidate B to candidate A rank candidate B
>insincerely high.
>Markus Schulze