[EM] Forest--EQTOP-MPO MAMPO example

Michael Ossipoff mikeo2106 at msn.com
Mon Mar 26 03:31:17 PDT 2007


Example with EQTOP - MPO MAMPO:

1000 voters:

380: AB
124: B
124: CB
124: DB
124: EB
124: FB

It’s obvious that this example is a failure example for EQTOP-MPO MAMPO with 
the votes-only counterparts of SFC and SDSC. But I’ll demonstrate that 
obvious fact anyway, at the end of this message.

Note that, in this example, the A voters aren’t even truncating or using any 
kind of offensive strategy.
That suggests that Steve Eppley’s name for votes-only SFC 
(“Truncation-Resistance“) isn’t general enough.
Likewise, the well-known IRV fails without truncation or any offensive 

By the way, it was Steve Eppley who first proposed the votes-only 
counterpart to SFC. I didn’t like it because (as I discussed yesterday) it 
doesn’t tell the important guarantee of SFC that I want to tell. It’s lack 
of applicability to all methods is another reason to not accept is as a 
replacement for SFC.

If people would prefer, I’ll 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.

I’ll do that because it’s true that my preference criteria are a little less 
convenient for rank methods. And they require information, preferences, that 
needn’t 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 it’s 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, there’s 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 can’t even really be 
intended) “votes”.

Of course here’s 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 don’t 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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