If the only options left are ones where a person can't make it, their
ballot shouldn't influence the result any more. Similarily when there
are only options which are questionable that ballot should have a lower
weight.
We do this by attaching a weight to each option, where real
choices get a weight of 1 and pseudo-choices (like "none of the
above") get a lower weight (theoretically that should be 0, but let's
keep that configurable). When constructing the ballots each vote gets a
monotonically decreasing weight. As options are eliminated in each
round, the weight of the ballot is recalculated as the maximum weight of
all remaining options. So this starts at 1 for all ballots, but drops as
more favourable options are eliminated, possibly down to 0 where a
ballot ceases to have an effect.
Peter J. Holzer
187718f360