In January 1997 I posed the question for Condorcet [EM] advocates:
"What plausible set of expectations about the votes of others could I
have that would give me a rational incentive, in Condorcet
(margins-of-defeat), to truncate but not to reverse order?"
If there was an answer, I missed it. If there is no answer, then one
should not worry about the possible effects of "truncation" in Young's
method. On the other hand, Markus has shown that in Condorcet [EM] there
is an incentive for insincere equal rankings at the top of one's ballot
(if one's preferences among favorites are weak compared to one's fear of
the worst), and of course there is always an incentive in Condorcet
[EM]for insincere random choices at the bottom, as between candidates
about whom one knows nothing.
IMHO, examples showing that "truncation" can be an effective insincere
strategy under one tiebreak method but not another are not meaningful if
both methods also allow a stronger insincere strategy in the same
situation to achieve the same end -- for example, order-reversal by half
as many voters as the number who would have needed to truncate in order
to change the outcome under the first method.
-- Hugh Tobin