Return to the discussion of instant runoff voting (IRV)
in Exercise S6.
(a) Consider the following IRV ballots of five voters:
Which—if any—of the five voters have an incentive to vote
strategically? If so, who and why? If not, explain why not.
(b) Consider the following table, which gives the IRV
ballots of a small town of seven citizens voting on five policy proposals put
forward by the mayor:
Assuming that all candidates (or policies) that tie for
the fewest votes are eliminated at the same time, under what conditions is an
eventual majority winner guaranteed? Put another way, under what conditions
might there not be an unambiguous majority winner? (Hint: How important is it
for Evans, Foster, and García to fill out their ballots completely?) How will
these conditions change if Harris moves into town and votes?