Partitioned Matching Games for International Kidney Exchange

We introduce partitioned matching games as a suitable model for international kidney exchange programmes, where in each round the total number of available kidney transplants needs to be distributed amongst the participating countries in a "fair" way. A partitioned matching game $(N,v)$ is defined on a graph $G=(V,E)$ with an edge weighting $w$ and a partition $V=V_1 \cup \dots \cup V_n$. The player set is $N = \{1, \dots, n\}$, and player $p \in N$ owns the vertices in $V_p$. The value $v(S)$ of a coalition $S \subseteq N$ is the maximum weight of a matching in the subgraph of $G$ induced by the vertices owned by the players in $S$. If $|V_p|=1$ for all $p\in N$, then we obtain the classical matching game. Let $c=\max\{|V_p| \; |\; 1\leq p\leq n\}$ be the width of $(N,v)$. We prove that checking core non-emptiness is polynomial-time solvable if $c\leq 2$ but co-NP-hard if $c\leq 3$. We do this via pinpointing a relationship with the known class of $b$-matching games and completing the complexity classification on testing core non-emptiness for $b$-matching games. With respect to our application, we prove a number of complexity results on choosing, out of possibly many optimal solutions, one that leads to a kidney transplant distribution that is as close as possible to some prescribed fair distribution

Cooperation in Multiorganization Matching

International audienceWe study a problem involving a set of organizations. Each organization has its own pool of clients who either supply or demand one unit of an indivisible product. Knowing the profit induced by each buyer-seller pair, an organization’s task is to conduct such transactions within its database of clients in order to maximize the amount of the transactions. Inter-organizations transactions are allowed: in this situation, two clients from distinct organizations can trade and their organizations share the induced profit. Since maximizing the overall profit leads to unacceptable situations where an organization can be penalized, we study the problem of maximizing the overall profit such that no organization gets less than it can obtain on its own. Complexity results, an approximation algorithm and a matching inapproximation bound are given

Cooperation in multiorganization matching ∗

We study a problem involving a set of organizations. Each organization has its own pool of clients who either supply or demand one unit of an indivisible product. Knowing the profit induced by each buyer/seller pair, an organization’s task is to conduct such transactions within its database of clients in order to maximize the amount of the transactions. Inter-organizations transactions are allowed: in this situation, two clients from distinct organizations can trade and their organizations share the induced profit. Since maximizing the overall profit leads to unacceptable situations where an organization can be penalized, we study the problem of maximizing the overall profit such that no organization gets less than it can obtain on its own. Complexity results, an approximation algorithm and a matching inapproximation bound are given