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by dllthomas 1828 days ago
> I think the instant-runoff voting which NYC is using is mostly strategy proof (i.e. strategies only exist in rare circumstances)

The very comment you are replying to pointed out that "a lot of NYC voters aren't ranking either Wiley or Adams" which is a failure to apply strategy where it manifestly exists. "There are front runners" doesn't seem to be a rare circumstance.
1 comments
singhrac 1826 days ago
Well, you're right, but we mean different things. These voters are failing to rank their true preferences (you and I believe), which is going to lead to a less optimal outcome than if they had. But if they did rank their true preferences (i.e. they are ok with Wiley or Adams, but just at the bottom of their list), then it would be fine.

This is a valid communication problem with ranked lists, but it's not that there exists a "strategy" per se besides ranking all of your acceptable outcomes.

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dllthomas 1825 days ago
> These voters are failing to rank their true preferences (you and I believe)

I expect they are being honest about their preference order, but that this has less of an impact on the outcome (in whatever direction they desire) than if they had been dishonest about their preference order.

This does assume that they actually prefer one of the front-runners to the other by a more-than-negligible margin; perhaps that isn't the case.

> This is a valid communication problem with ranked lists, but it's not that there exists a "strategy" per se besides ranking all of your acceptable outcomes.

There were more than six candidates, and voters could only rank their top five. Voters with more than 5 "acceptable outcomes" need to vote strategically when they get near the bottom of that list.

Alternatively, there is also no such thing as "strategy" in FPTP - "you just vote for one of your acceptable outcomes". That's... not a useful definition of the words involved.

Edited to add: It occurs to me that perhaps you weren't aware of the cutoff in the NYC case and were speaking of IRV with a full list? In that case I agree that strategy being necessary is substantially more rare, leaving aside for the moment whether it is sufficiently rare.

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