Summability criterion: Difference between revisions

[[IRV]] does not comply with the summability criterion. In the IRV system, a count can be maintained of identical votes, but votes do not correspond to a summable array. The total possible number of unique votes [[Space_of_possible_elections|grows factorially with the number of candidates]].

It is possible to reduce the amount of data required to call an IRV election by instead storing a Plurality count for all <math>2^c</math> ways to eliminate some subset of the candidates. This gives an array of <math>2^{c-1}c - 2^c + 1 = O(2^cc)</math> elements; but that is still not polynomial.