Abstract(s)
We study the random assignment of indivisible objects among a set of agents with strict
preferences. We show that there exists no mechanism which is strategy-proof, envyfree
and unanimous. Then we weaken the latter requirement to q-unanimity: when each
agent ranks a different object at the top, then any agent shall receive his most preferred
object with probability of at least q. We show that if a mechanism satisfies strategyproofness, envyfreeness, ex-post weak non-wastefulness, ex-post weak efficiency and
q-unanimity, then q must be smaller than or equal to 2
|N|
(where |N| is the number of
agents). We introduce a new mechanism called random careless dictator (RCD) and
show that RCD achieves this maximal bound. In addition, for three agents, RCD is
characterized by the first four properties.
JEL Classification: D63, D70.