IRVDuels

class svvamp.IRVDuels(population, **kwargs)

IRV with elimination duels.

Inherits functions and optional parameters from superclasses ElectionResult and Election.

Example:

>>> import svvamp
>>> pop = svvamp.PopulationSpheroid(V=100, C=5)
>>> election = svvamp.IRVDuels(pop)

Principle: each round, perform a duel between the two least-favorite candidates and eliminate the loser of this duel.

Even round r (including round 0): the two non-eliminated candidates who are ranked first (among the non-eliminated candidates) by least voters are selected for the elimination duels that is held in round r+1.

Odd round r: voters vote for the selected candidate they like most in the duel. The candidate with least votes is eliminated.

This method meets the Condorcet criterion.

We thank Laurent Viennot for the idea of this voting system.

CM(): Non-polynomial or non-exact algorithms from superclass Election.

ICM(): Exact in polynomial time.

IM(): Non-polynomial or non-exact algorithms from superclass Election.

not_IIA(): Exact in polynomial time.

TM(): Exact in polynomial time.

UM(): Non-polynomial or non-exact algorithms from superclass Election.

See also

ExhaustiveBallot, IRV, ICRV, CondorcetAbsIRV. CondorcetVtbIRV.

candidates_by_scores_best_to_worst

1d array of integers. Candidates are sorted in the reverse order of their elimination.

By definition, candidates_by_scores_best_to_worst[0] = w.

scores

2d array.

For even rounds r (including round 0), scores[r, c] is the number of voters who rank c first (among non-eliminated candidates).

For odd rounds r, only the two candidates who are selected for the elimination duels get scores. scores[r, c] is the number of voters who vote for c in this elimination duel.

w

Integer (winning candidate).