[EM] Forest--EQTOP-MPO MAMPO example
Michael Ossipoff
mikeo2106 at msn.com
Mon Mar 26 03:31:17 PDT 2007
Forest--
Example with EQTOP - MPO MAMPO:
1000 voters:
380: AB
124: B
124: CB
124: DB
124: EB
124: FB
Its obvious that this example is a failure example for EQTOP-MPO MAMPO with
the votes-only counterparts of SFC and SDSC. But Ill demonstrate that
obvious fact anyway, at the end of this message.
Note that, in this example, the A voters arent even truncating or using any
kind of offensive strategy.
That suggests that Steve Eppleys name for votes-only SFC
(Truncation-Resistance) isnt general enough.
Likewise, the well-known IRV fails without truncation or any offensive
strategy.
By the way, it was Steve Eppley who first proposed the votes-only
counterpart to SFC. I didnt like it because (as I discussed yesterday) it
doesnt tell the important guarantee of SFC that I want to tell. Its lack
of applicability to all methods is another reason to not accept is as a
replacement for SFC.
If people would prefer, Ill use the votes-only counterparts of SFC and
SDSC, when evaluating rank methods (but not when comparing them to nonrank
methods). I do so with the understanding that my preference versions are the
actual criteria, and the votes-only versions are only a convenience, when
comparingrank methods to eachother.
Ill do that because its true that my preference criteria are a little less
convenient for rank methods. And they require information, preferences, that
neednt be involved when comparing rank methods to each other.. And we all
know that only rank methods are going to pass SFC and SDSC anyway. For that
reason the preference versions could even be called inelegant, when
comparing only rank methods.
But, when its necessary to evaluate or compare to nonrank methods, the
elegance comparison between votes-only and preference is reversed. Then, the
preference criteria are the ones that are elegant, because of their uniform
applicability to all methods.
When comparing all methods, theres nothing elegant or convenient about the
votes-only criteria, and their use of FARCS. In fact, votes-only loses its
meaning when FARCS calls intended rankings (which cant even really be
intended) votes.
Of course heres why the example is a failure example for EQTOP - MPO MAMPO,
with votes-only SFC & SDSC:
A majority rank B over A, but no majority rank anyone over B. But A wins.
A majority rank B over A, and dont rank A. But A wins.
For applying the preference SFC and SDSC, it would be necessary to state
preferences, and to make the rankings of the {B,C,D,E,F} voters complete, to
satisfy the sincerity requirement of SFC. But EQTOP-MPO MAMPO fails
preference SFC and SDSC too.
Mike Ossipoff
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