[EM] Omission in voting definition yesterday

[MIKE OSSIPOFF]

When I posted my definition of fullly voting one candidate over another 
yesterday, I left out an important clause:

"...if all the candidates but X & Y are deleted from the rankings, and..."


That clause is in the definitions of voting one candidate over another, and 
it is needed also in the definition of fully voting one candidate over 
another.

So the complete definition of fully voting one candidate over another is:

A voter fully votes X over Y if s/he votes in such a way that if there were 
an even number of voters, and half of them voted in that way, and if all the 
candidates but X & Y were deleted from the ballots, then it is impossible 
for Y to be the unique winner, no matter how the other half vote.

[end of definition of fully voting one candidate over another]

Another error in that posting: I said that SDSCf closes the loophole that 
allows some piont systems to meet SDSC. That isn't correct. Those point 
systems meet SDSCf too. In fact SDSCf is easier to meet than SDSC.

Here's a criterion that point systems can't meet:

It should be possible to fully vote X over Y while fully voting Y over Z.

[end of definition]

I don't know what call that. Maybe Serial [or sequential?] Voting-Over 
Criterion. Condorcet meets that criterion.

Mike Ossipoff

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