# [EM] Re: Miscellaneous comments on MMPO & MDDA

MIKE OSSIPOFF nkklrp at hotmail.com
Mon Jun 27 17:33:25 PDT 2005

```Kevin--

You said:

Something that strikes me as odd about SFC is that it guarantees that a
certain majority can do something which, if they knew that they were part of
this majority, they wouldn't need to do anyway.

I don't know--whether the method is wv or Approval, don't they need to vote
the CW over Y, to make Y lose, even if they're sure that they're a CW>Y
majority? (that majority probably includes people to whom the CW is
favorite, and probably wouldn't exist without them).

But sure, if they had that information, they could vote informedly and
successfully in Approval.

That's a valid criticism of the majority defensive strategy criteria.

Watching that progressive vote in that Internet poll gave me new respect for
criteria that are about a voter in isolation, and not about majorities, the
CW, or whether everyone votes sincerely. Because the voter might not know
that large-scale information.

You continued:

It almost seems to me that SFC is a criterion designed to reduce possible
complaints about the result.

True, a judge after the electdion can look at the majority information and
say, "Yes, this was fair to the majority". But that doesn't help the voter's
strategy if s/he doesn't have such information.

You continued:

In other words, it must *never* be optimal strategy (i.e., be best for
{a,b})
to vote A=B. The problem with this is that most likely the optimal strategy
will
be to vote the more viable candidate over the less viable one.

If you insist on this latter property and FBC at the same time, then the
probability that the winner comes from {a,b} must be totally independent of
whether you vote A=B, A>B, or B>A.

The latter property is satisfied by "MinGS" ("elect the candidate whose
fewest
votes for him in some contest is the greatest") and Woodall's DSC method
(which
is not a pairwise count method).

Just at first glance, that sounds pretty good, guaranteeding that the chance
of the winner coming from {Dean, Nader} is completely independent of how you
order those two. Your ordering of them depends only on which you choose over
the other. Isn't that a further reduction in the lesser-of-2-evils problem?

I haven't looked at MinGS or DSC, and maybe they have some big disadvantage,
but it's my policy that even the most unlikely solution deserves a look.

I'd said:

>CR, MMPO, and MDDA are all equivalent to Approval in an
>acceptable/unacceptable situation when the voter votes optimally (with
>power truncation available in MMPO & MDDA). Is that a general fact, that
>all FBC-complying methods are equivalent to Approval under those
>conditions, or are there exceptions?

You replied:

I'm a bit confused when you say that MMPO is "equivalent to Approval in an
acceptable/unacceptable situation." If you use MMPO on approval ballots, you
don't get the same results as under Approval. In fact, the approval loser
can
win.

I only meant if, for everyone, it's an acceptable/unacceptable situation,
and power truncation is available and everyone votes optimally.

to be continued.

There isn't time to check this for errors, but I'll hope for the best.

Mike Ossipoff

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