James G-A replying to Mike, on the topic of the burying strategy...
Mike:
>>For instance, I said, and contnue to say that emphasis on methods'
>>"vulnerability" to strategy completely misses the point.
>>So does the treatment of what you call "burying strategy" as a separate
>>method problem from the strategy problems of Plurality and IRV.
James:
>It is a separate problem if it succeeds.
Mike:
>No! If it succeeds, it's indistinguishable and identical to what happens
>in
>Plurality and IRV without anyone using offensive strategy.
Let's get this straightened out before we proceed. I asserted that the
burying strategy, if successful, can produce problematic results that
can't occur in IRV. You disagreed, so I'll give an example. This is not a
new example, but rather one that I've been using since summer 2003.
Ex. 1: Sincere preferences expressed:
46: A>B>C
44: B>A>C
5: C>A>B
5: C>B>A
Ex. 1: Pairwise comparisons:
A>B 51-49
A>C 90-10
B>C 90-10
Ex. 1 winner: A
Ex. 2: Expressed preferences (some insincere):
46: A>B>C
44: B>C>A (sincere was B>A>C)
5: C>A>B
5: C>B>A
Ex. 2: Pairwise comparisons:
A>B 51-49
C>A 54-46
B>C 90-10
Ex. 2 winner: B
When I bring this example up, you usually state that the A voters will
be
able to prevent the strategy by truncating (if WV is being used), and I
agree with you there.
But now, I'm talking about a scenario where no other voting bloc
responds
with counterstrategy, and the burying strategy is successful. If that's
the case, B would win here instead of A, the sincere CW.
IRV will pick A either way, and in general IRV will not be vulnerable to
manipulation in this example.
So, if the strategy is successful, it causes a problem that is not found
in IRV. Which is to say that the burying-vulnerable methods contain at
least the _possibility_ of a type of problem occurring that cannot occur
in IRV. How likely is the possibility? That is another, much more
complicated discussion.
>
sincerely,
James
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