[EM] Cumulative Vote equivalence to Plurality

[Forest Simmons]

Someone (Kevin or Bart or both) recently reminded us that the usual
version of Cumulative Voting is strategically equivalent to Plurality.

However the recent proposal allowing both positive and negative votes with
the sum of absolute values limited, is different: it turns out to be
strategically equivalent to a method that (like plurality) allows only one
mark, but that mark can be either positive or negative, i.e. you can vote
for a candidate or against a candidate, but not both.

That would definitely be an improvement over plurality, and in the case of
three candidates it would be equivalent to Approval.  But with four or
more candidates, Approval would be better for the usual reasons.

Forest