Abstract
Shortlisting of candidates—selecting a group
of “best” candidates—is a special case of multiwinner elections. We provide the first in-depth study
of the computational complexity of strategic voting
for shortlisting based on the most natural and simple voting rule in this scenario, `-Bloc (every voter
approves ` candidates). In particular, we investigate
the influence of several tie-breaking mechanisms
(e.g. pessimistic versus optimistic) and group evaluation functions (e.g. egalitarian versus utilitarian)
and conclude that in an egalitarian setting strategic
voting may indeed be computationally intractable
regardless of the tie-breaking rule. We provide
a fairly comprehensive picture of the computational
complexity landscape of this neglected scenario