This paper studies the problem of assigning a set of indivisible objects to a set of agents when monetary transfers are not allowed and agents reveal only ordinal preferences, but random assignments are possible. We offer two characterizations of the probabilistic serial mechanism, which assigns...

A new mechanism was introduced in New York City and Boston to assign students to public schools. This mechanism was advocated for its superior fairness property, besides others. We introduce a new framework for school-choice problems and two notions of fairness in lottery design based on ex-ante...

We consider the standard indivisible object allocation problem without monetary transfer and allow each object to have a weak priority over agents. It is well known that generally in such a problem stability (or no justified-envy) is not compatible with efficiency. We characterize the priority...

We consider the problem of randomly assigning n indivisible objects to n agents. Recent research introduced a promising mechanism, the probabilistic serial that has superior efficiency properties than the most common real-life mechanism random priority. On the other hand, mechanisms based on...

Many universities in the US o¤er on-campus housing opportunities to incoming as well as already enrolled students. Recent research has theoretically as well as experimentally shown that the most common student assignment mechanism used in the US is subject to serious efficiency losses. In this...

An increasingly popular practice for student assignment to public schools in the U.S. is the use of school choice systems. The celebrated Gale-Shapley student-optimal stable mechanism (SOSM) has recently replaced two de…ficient student assignment mechanisms that were in use in New York City...

Many school districts in the US. employ centralized clearing houses to assign students to public schools. An important potential threat against any school choice mechanism is the tendency of schools to circumvent the procedure via two kinds of strategic manipulation: manipulation via capacities...