[EM] SODA sometimes FBC-safe

MIKE OSSIPOFF nkklrp at hotmail.com
Thu Mar 1 13:38:33 PST 2012


You wrote:

 with SODA, it does help, because you can know ex ante (by looking at 
the predeclared preferences) when you are safe by FBC. That is, if you 
prefer A>B, and B prefers A, or A prefers B, or A and B both prefer a
 certain viable C, then you are safe. Only if B prefers the most-viable 
third candidate C, but A is indifferent between B and C, then you might 
consider a favorite-betraying vote for B. And even then, it's only 
appropriate if A very nearly, but not quite, is able to win... not 
exactly the situation where favorite betrayal is the first thing on your

This is a specific enough circumstance that 
favorite-betraying strategy would never "take off" and become a serious 
factor in SODA.
 SODA, you can give that as a solid ex-ante guarantee to most voters, 
just not quite all of them. This is unlike the situation in most voting 
systems, where you can make no solid guarantees before the vote unless 
you can make them to all voters.


Ok yes, as you say, that's a very different situation from the ordinary FBC-failure, because, for most people there is known to be no favorite-burial need. The favorite-burial problem really
exists when there's uncertainty for everyone, or for a large percentage of the voters, which isn't the case with SODA.

Mike Ossipoff

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