Fair Division under Ordinal Preferences: Computing Envy-Free Allocations of Indivisible Goods
Sylvain Bouveret, Ulle Endriss, Jérôme Lang

Abstract:
We study the problem of fairly dividing a set of goods amongst a group
of agents, when those agents have preferences that are ordinal
relations over alternative bundles of goods (rather than utility
functions) and when our knowledge of those preferences is
incomplete. The incompleteness of the preferences stems from the fact
that each agent reports their preferences by means of an expression of
bounded size in a compact preference representation
language. Specifically, we assume that each agent only provides a
ranking of individual goods (rather than of bundles). In this context,
we consider the algorithmic problem of deciding whether there exists
an allocation that is possibly (or necessarily) envy-free, given the
incomplete preference information available, if in addition some mild
economic efficiency criteria need to be satisfied. We provide simple
characterisations, giving rise to simple algorithms, for some
instances of the problem, and computational complexity results,
establishing the intractability of the problem, for others.