[EM] CDTT, IRV is IRV with pre-elimination

MIKE OSSIPOFF nkklrp at hotmail.com
Sun May 29 21:36:42 PDT 2005

Of course sometimes what something is called can affect its acceptance. 
Among people who like or advocate IRV, a method that uses IRV to choose from 
some selection set should be called "IRV with pre-elimination".

If the selection set is a good enough one, then even IRV can't do any harm 
when choosing from it. And "IRV with pre-elimination" implies that the 
selection set is just some preliminary elimination to prepare for IRV. So 
that name makes IRV sound more important and central to the method than it 
is, when really, with a good enough selection set, it doesn't even matter 
how we choose from it.

I don't understand the difference between CDTT,IRV and CDTT//IRV. If the 
recent message discussing that difference explains the difference, and if I 
want to find out, then I should re-read that message. If that discussion is 
considered a good explanation of the difference, then of course there's no 
reason to explain it again.

Recently I've heard of some methods and sets that arre similar, or have 
similar names. So I don't know exactly what the CDTT is, except that it's a 
selection set.

In general, the set of candidates who could be elected without violating a 
certain criterion can conveniently be named for that criterion.

For instance, the set of candidates who could be elected without violating 
BC could be called "The BC set". That's a brief and convenient name.

If the BC set is the one that is called the CDTT, and if it was being called 
the CDTT before Steve posted BC, then I'll start calling the BC set the 
CDTT. Likewise with any other name that the BC set had before Steve posted 

And, for example, if a method uses some other method to choose from the BC 
set, it could be called BC//method. That's just like CDTT//IRV

BC// methods meet the majority defensive strategy criteria, SFC, GSFC, WDSC, 
and SDSC. And choosing the tiebreaker gives an opportunity to add some other 
desirable property, tailoring the overall method. But of course a 
disadvantage of a compound method, a "//" method, is that it's more 
complicated and therefore not as publicly acceptable. That goes for 
Approval/ranking hybrids too.

Mike Ossipoff

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