An allocation of indivisible items among n ≥ 2 players is proportional if and only if each player receives a proportional subset—one that it thinks is worth at least 1/n of the total value of all the items. We show that a proportional allocation exists if and only if there is an allocation...

We present a new model for cost sharing in minimum cost spanning tree problems, so that the planner can identify the agents that merge. Under this new framework, and as opposed to the traditional model, there exist rules that satisfy merge-proofness. Besides, by strengthening this property and...

In the context of cost sharing in minimum cost spanning tree problems, we introduce a property called No Advantageous Merging. This property implies that no group of agents can be better off claiming to be a single node. We show that the sharing rule that assigns to each agent his own connection...

In this paper, we consider two-sided, many-to-one matching problems where agents in one side of the market (hospitals) impose some distributional constraints (e.g., a minimum quota for each hospital). We show that when the preference of the hospitals is represented as an M-natural-concave...

Regional imbalance of doctors is a serious issue in many countries. In an attempt to average the geographical distribution of doctors, the Japanese government introduced ``regional caps'' recently, restricting the total number of medical residents matched within each region. Motivated by this...

A polluted river network is populated with agents (e.g., firms, villages, municipalities, or countries) located upstream and downstream. This river network must be cleaned, the costs of which must be shared among the agents. We model this problem as a cost sharing problem on a tree network....

Water is essential for life. However, the basic problem of water resource allocation has been that water tends to be over-allocated. Demand for water exceeds the available supply. Essentially, the water economy is bankrupt. Bankruptcy problems have been almost exhaustively studied in the...

The successful formation and long-term stability of a cooperative venture is often linked to the perceived fairness of the associated cost or resource allocation. In particular, the effectiveness of such collaborations can be hampered by the lack of a consensus view on what basis should be used...

As it is known, there is no rule satisfying Additivity in the complete domain of bankruptcy problems. This paper proposes a notion of partial Additivity in this context, to be called m-additivity. We find that m-additivity, together with two quite compelling axioms, anonymity and continuity,...

In U.S. presidential elections, voters in noncompetitive states seem not to count—and so have zero voting power, according to the Banzhaf and other voting-power indices—because they cannot influence the outcome in their states. But because the electoral votes of these states are essential to...