Talk:Instant-runoff voting: Difference between revisions

== RE: Criticisms, commenting on later-no-harm and later-no-help ==

If IRV is ignoring most of the ballot (to satisfy later-no-harm and later-no-help) at the expense of center squeeze and favorite betrayal, then can we fix that and still call it IRV? Although I thought later-no-harm was the gold standard of a fair vote, my improved IRV fails later-no-harm and later-no-help. I'm happy that it does.

An example of SV failing Later-no-harm.

46 A

10 B

44 C>B

SV 3 way tie which results in one of 3 candidates being elected by random draw.

(IRV elects A). What happens when supporters of a go too far?

46 A>B

10 B

44 C>B

SV elects B, thereby A loses a third of a chance to win by adding B as a preference (IRV still elects A, no harm done). By definition, I believe this violates later-no-harm.

An example of SV failing Later-no-help.

12 A

8 B>A

6 C>B

Standard Vote elects B (IRV elects B).

Variation 1: When 3 of the A voters change their votes to C, the result is a three way tie to be broken by random draw (IRV elects A, in effect failing later-no-help).

9 A

3 C

8 B>A

6 C>B

Variation 2: Alternatively, if those 3 voters had changed their ballots to A>C it’s the same tie (IRV still elects B, it doesn’t help).

9 A

3 A>C

8 B>C

6 C>B

In both variation 1 and 2, the probability of electing A has increased. A goes from total defeat to a small chance. By definition, I believe this violates later-no-help.

[[User:RalphInOttawa|RalphInOttawa]] ([[User talk:RalphInOttawa|talk]]) 01:04, 4 January 2024 (UTC)