[EM] Compatibility

[Kristofer Munsterhjelm]

Juho wrote:
> Let's say that there are three different criteria that an election 
> method should meet. They are related to three different strategic voting 
> related problems. As in the world of security also election methods are 
> as vulnerable to strategic voting as their weakest link. In this 
> situation there may be a solution that almost meets all the three 
> criteria but does not meet any of them fully. That solution is often 
> (but not always) the best solution.
> 
> So, there are patterns where a good method should meet only a strict 
> subset of the requirements that some competing methods meet. One may 
> thus improve a method by making it incompatible to some (good) criterion 
> that it earlier met. The point is that compatibility with various 
> criteria should often not be an on/off comparison but a richer analysis 
> where also partial and almost complete compatibilities are counted.

This seems to be an issue of the criteria being too demanding. Consider, 
for instance, independence from covered candidates. I think Forest 
Simmons said (in private correspondence) that IFCC implies nonmonotonicity.
If one considers monotonicity important, but also would like to have the 
method be independent of as many types of non-winning candidates as 
possible, the natural next thing to do is to ask: how strong can we make 
this independence criterion and still satisfy monotonicity?

Similarly for your own situation; say that Smith compliance breaks 
something else you want. Then you can try to find out what that thing 
that you want is, and afterward attempt to find the closest thing to 
Smith compliance that doesn't break it.

(For the record, I think Smith compliance is a good thing, and that 
perhaps one should go even further - thus my interest in uncovered set 
methods, IPDA, etc.)