[EM] voter strat & 2-party domination under Condorcet voting

[Kevin Venzke]

Warren,

I believe it's safe to say that all deterministic rank methods which disallow
equal ranking must fail the "favorite betrayal" criterion. You don't have to
prove that for individual rank methods.

You started your message like this:

--- Warren Smith <wds at math.temple.edu> a écrit :
> On the probability that insincerely ranking the two frontrunners max and min, is
> optimal voter-strategy in a Condorcet election.

But then wrote mostly about favorite betrayal. I am sure that what is more
controversial is the notion that voters should typically rank one frontrunner
"min."

You should consider the case that equal ranking and truncation are permitted.
I believe disallowing truncation, especially, would be a disaster under
Condorcet.

> Summary.
> Adam Tarr in previous posts had questioned my claim that this this plurality-like voter
> strategy could ever be optimal in Condorcet elections.  He said
> "I can't easily imagine a scenario where it is useful in Condorcet."

Adam had written this:
>I don't debate that the "more-favored front runner first, less-favored
>front runner last" strategy is useful (often optimal) in Borda, but I
>can't easily imagine a scenario where it is useful in Condorcet.  Nor
>have I ever heard it advocated.  It does not seem "obvious" to me.

It's the "less-favored front runner last" part that seems to not be obvious.
In Warren's argument, the less-favored frontrunner *was* the sincere last
preference, so that ranking him last isn't even a strategic move.

>    http://math.temple.edu/~wds/crv/RangeVoting.html
> "Why range is better than Condorcet" discussion, perhaps because said example was in the
> subpage  http://math.temple.edu/~wds/crv/IncentToExagg.html.
> But now the present discussion shows that Tarr was maximally wrong: this strategy
> is ALWAYS the right move.

On the "IncentToExagg" page you discuss favorite betrayal, but not why voters
should rank the worst frontrunner last.

Kevin Venzke



	

	
		
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