Re: Constitutional amendment: Condorcet/Clone Proof SSDvotetallying
On Sat, May 31, 2003 at 02:23:07AM +1000, Anthony Towns wrote:
> On Fri, May 30, 2003 at 10:48:06AM -0400, Nathanael Nerode wrote:
> > In a pure Condorcet system with a default option, lying about the
> > acceptability of A *doesn't* help B.
> 40 C A B
> 30 A B C
> 20 B C A
> C defeats A 60:30, A defeats B 70:20, B defeats C 50:40; the weakest
> defeat is dropped, C wins. If the ABC voters switch to:
> 30 B C A
> then B wins -- lying about the acceptability of A *does* help B, even in a
> pure Condorcet case (well, pure CpSSD -- although even in pure Condorcet,
> B winning is probably preferable to no result).
This is the point that I noted complicates the analysis: Strategic
voting can work in Condorcet+CpSSD. It just works less often than
in the proposed system. If you carry out more examples, I think
you'll conclude that it works in appreciably fewer cases, though I
don't know how to quantify this.
9 ABD A>B 12:8
6 BAD A>D 15:5
3 DAB B>D 15:5
B can swap and make D>A 11:9, but in Condorcet/CpSSD A still wins.
I think this is related to the Strong Defensive Strategy Criterion.