Ranking can violate secrecy.

[Bart Ingles]

Mike Ositoff wrote:
> 
> Interesting. That hadn't occurred to me, about the possibility
> of a bought voter identifying himself by a unique ranking.
> It sounds possible, and it sounds like possibly a fatal problem
> for rank-balloting in many-candidate elections. Is there a
> solution?
> 
> Mike

Sure.  Limit the number of ranks allowed, with only one vote per
ranking.  If you want to allow votes for additional candidates, you can
allow the voter to rank them equally in the next-to-last position (as
well as in the last position, which would be equiv. to truncation).

Note that allowing multiple equally-ranked candidates in all positions
would increase the opportunities for a unique pattern.  If you want to
do this you would need to reduce the max. number of ranks even further
to compensate.