[EM] IRV is best method meeting 'later no harm'?

[seppley at alumni.caltech.edu]

Can it be said that Later No Harm (LNH) is satisfied by the variation of
IRV that allows candidates to withdraw from contention after the votes are
cast?

Similar to truly condorcetian methods, Withdrawal//IRV would presumably
tend to elect candidates who take median positions on the issues.  That
would create an incentive for candidates who want to win to take median
positions.

I'm not claiming median positions are necessarily best.  But I do believe
there are significant advantages to voting methods that induce candidates
who want to win to take median positions:  Less polarization and less
demagoguery.  Stability & incrementalism, since issues (e.g., abortion)
will tend to get settled until the median position changes significantly. 
Accountability on more issues, since a candidate who takes a non-median
position on some issue would be risking that another candidate will take
the (majority-preferred) median position and match his/her positions on
other issues, and also since many other issues would already be settled
(in an accountable way: the median).  Increased competition, since such
methods would by necessity have very little spoiling (unlike plain IRV). 
Reduced corruption, since accountability on more issues and increased
competition would allow voters to rank less corrupt candidates over more
corrupt candidates.  Reduced cost of campaigning, since "big tent" parties
(if they continue to exist) would no longer need to conduct primary
elections to winnow their contenders to one per office.

* * *

By the way, if my understanding is correct, IRV is not Single Transferable
Vote (STV), the single-winner voting method used in Australia & Ireland. 
IRV severely limits the number of candidates each voter can rank (to 3, if
my understanding is correct) whereas STV allows (or requires) each voter
to rank every candidate.  STV satisfies LNH, and many people may consider
it to be somewhat better than IRV. (STV facilitates greater competition
and less spoiling, especially if candidates are permitted to withdraw
after the votes are cast.)

Since IRV is said to satisfy LNH, then one must say Plurality Rule
satisfies LNH too, because Plurality Rule can be viewed as just a
variation of IRV with a smaller limit (one candidate per voter).

* * *

If Withdrawal//IRV and Plurality Rule satisfy LNH, then I think it's
reasonable to say that so do some methods in the Voting for a%2