[Note: I am not subscribed to the list, so please copy me on replies.] Instant Run-off Voting, Approval voting, and Plurality are all the same voting rule applied to ballot sets with differing characteristics. The rule operates in four modes: Ties allowed; Multiple Rankings Allowed; Neither; and Both. The voting rule is called Instant Run-off Approval Voting. Consider a ballot with the following ranks: 1 - A 2 - B 2 - C 3 - D 4 - E Round 1 votes: 11 A 15 B 17 C 22 D 20 E During the first round, A is the plurality loser. We eliminate A and move ballots to the second-ranked candidate. Five first-rank-A ballots ranked each of D and E second (no tie). This particular ballot ties B and C for second; thus we cast two votes: 16 B 18 C 27 D 25 E B is the plurality loser. Ten of those go to D; five go to E; this particular ballot ranked C tied with B, so does not move. 18 C 37 D 30 E The various configurations: 1. Ties, Multiple Ranks: Instant Run-off Approval Voting. 2. No Ties, Multiple Ranks: Instant Run-off Voting. 3. Ties, One Rank: Approval Voting. 4. No Ties, One Rank: Plurality. This generalization can extend Tideman's Alternative Smith and Instant Run-off Voting to ballots with ties. Such extensions may change the characteristics of the resulting vote rule, such as its resistance to tactical voting and nomination. I don't know how allowing ties in Tideman's Alternative Smith or IRV affects tactical manipulation. IRAV has the obvious advantages of reducing ballot spoilage and increasing voter preference expressiveness. Gaps are irrelevant: if your rankings are 1 40 90 8000, that's just 1 2 3 4; treat it as such. All ballots are now valid.