[EM] Richard's criteria

[Richard Moore]

Mike,

Thanks for feedback. I will address as many points as I can tonight, 
but I will have to get back later with revised versions of the first 
four criteria.

  -- Richard

Mike wrote:
> Richard continued:
> 
> Here are my "votes-only" definitions:
> 
> SFC: If X beats all other candidates in pairwise comparisons, and
> a majority of ballots rank X over Y, then Y does not win.
> 
> I reply:
> 
> If, as seems to be the case, based on how it's written, that criterion 
> applies only to rank methods, then, for that reason, it isn't equivalent to 
> SFC.

It should probably include a clause, "The method allows full ranking 
of all candidates, and [insert remainder of criterion here]". But 
first I need to ascertain that *only* methods that allow full ranking 
can pass the criterion. And if not, then the issue needs to be dealt 
with some other way (I have an idea how, but would rather have the 
simplest fix necessary). There may be some other changes necessary 
since I overlooked the impact of one of the clauses in the original 
definition; I'll have to give it a closer look and rewrite it. The 
same applies to the votes-only GSFC, WDSC, and SDSC.

> Richard continued:
> 
> Note: The statement in the electionmethods.org commentary that
> "Compliance with SDSC means that a majority never needs any more than
> truncation strategy to defeat a particular candidate" is puzzling
> (truncation strategy is "falsely voting two candidates equal", is it
> not?).
> 
> I reply:
> 
> No it is not. If you don't include certain candidates in your ranking, then 
> you aren't voting for them. If you aren't voting for them, then there isn't 
> a compelling case that you're voting them any way, including equal. You're 
> leaving them out equally.

So you want readers to infer something (that truncation isn't the same 
as "voting candidates equal") that isn't implied in the definitions?

Consider this statement, from the same web page: "In order to 
understand SFC, one must also understand that there are two types of 
insincere votes: false preferences and truncated preferences. Voters 
truncate by terminating their rank list before their true preferences 
are fully specified (note that the last choice is always implied, so 
leaving it out is not considered truncation). Voters falsify their 
preferences, on the other hand, by reversing the order of their true 
preferences or by specifying a preference they don't really have." We 
can infer from this that (1) truncated preferences are not false 
preferences, since they have their own separate category; and (2) 
"voting two candidates equal" is not a case of a falsifying 
preference, since it is not enumerated in that category. That leaves 
wide open the interpretation that truncation is the same as "voting 
candidates equal", as long as we are not provided with a special 
definition of "voting candidates equal" such as the one you now suggest:

> A voter votes X equal to Y if s/he doesn't vote X over Y, and doesn't vote Y 
> over X, and votes X over someone, and votes Y over someone.
> 
> [end of definition of voting X over Y]

So in my next try at a votes-only definition I will have to take into 
account your new supporting definition.

> Richard continued:
> 
> Also, the statements in the commentary about "countering
> offensive order reversal" are completely irrelevant, since the need
> for defensive strategy is based on the opposing votes cast regardless
> of whether those votes are the result of offensive order reversal.
> 
> I reply:
> 
> It isn't quite clear why Richard thinks that the fact that the fact that 
> sincere votes can have the same effect as similarly voted strategic votes 
> means that it's irrelevant to speak of countering offensive order-reversal.
> 
> Is it meaningless to speak of blocking an intentional punch because someone 
> could also hit you accidentally, and that would be blocked too, by the same 
> block?

To quote the web page once again:

"Compliance with SDSC means that a majority never needs any more than 
truncation strategy to defeat a particular candidate, even when 
countering offensive order reversal by that candidate's voters."

"Even when" is typically used in English as an indicator that there is 
a potential (in this case, for the need to apply "more than truncation 
strategy") that exists in the presence of the stated condition but not 
in its absence. But that isn't true; that is what I was getting at. 
The sentence retains its meaning without the misleading "even when" 
clause.

> Richard continued:
> 
> FBC: For some set S of ballots, if R is the set of results that can
> occur when ballot B is added to S if candidate X is given the highest
> ranking on B, and R' is the set of results that can occur if ballot B
> is added to S when candidate X is not given the highest ranking on B,
> then either X is a member of R, or R' is a subset of R.
> 
> I reply:
> 
> I asked how a votes-only FBC equivalent could be written. Your criterion may 
> or may not be equivalent to FBC. From your other criteria in your posting, 
> I'd say the likelihood isn't promising.

It *is* FBC (with the necessary changes -- since as you pointed out 
these criteria must apply to more than ranked methods -- from "is 
given the highest ranking" to "is not voted lower than any other 
candidate", and from "not given the highest ranking" to "is voted 
lower than some other candidate". But don't take my word for it; study 
it carefully and try to find some way in which it's not equivalent.

> In any case, FBC is written in a way that clearly, directly & obvioiusly 
> speaks to a voter concern.
> 
> Why would anyone want to write it as Richard has written here (even if 
> Richard's criterion is equivalent to FBC)?

I wrote it in a way that would be mathematically useful, as a point of 
discussion, rather than for promotional purposes. Promotion of FBC is 
getting off of the topic; however, I'll paraphrase it without the 
mathematical language, in a form very similar to the existing 
language: "By voting another candidate over candidate X, a voter 
should never get a result that he could not get without doing so, 
unless he could get X as the winner without doing so."

> The above "FBC" wouldn't be publicly usable. If I tried, everyone would tell 
> me they have no idea what it's supposed to mean. And even for someone who 
> knows what it means, it doesn't speak directly, obviously and clearly to 
> voter concerns as my own version of FBC does.
> 
> So, even if it should turn out that Richard's "FBC" is equivalent to FBC, I 
> wouldn't adopt it or replace FBC with it.

A strange criticism, coming from the person who wrote just yesterday, 
"And If FBC can be written votes-only, that would help its acceptance."

  -- Richard