Max-Utility Matchings with Popularity via Critical Vertices
摘要
Let G be a bipartite graph where every vertex has a strict preference order over its neighbors. The preferences of a vertex over its neighbors extend naturally to preferences over matchings. A matching N is more popular than matching M if the vertices that prefer N to M outnumber those that prefer M to N. A matching M is popular if there is no matching more popular than M. Every stable matching is popular, thus popular matchings always exist in G and can be efficiently computed. We consider the following problem: edges in G have utilities and it is only max-utility matchings that are relevant. Our goal is to find a popular max-utility matching, i.e., a max-utility matching M such that there is no max-utility matching more popular than M. We show there always exists a popular max-utility matching; furthermore, such a matching can be efficiently computed. The popular critical matching algorithm is the key subroutine in our algorithm. Given a set of prioritized or critical vertices in G, we are interested in only those matchings that match as many critical vertices as possible. We call such matchings “critical” and seek a popular critical matching, i.e., a critical matching M such that there is no critical matching more popular than M. We show popular critical matchings always exist in G and a min-size/max-size such matching can be efficiently computed. We focus on max-size critical matchings and show a compact extended formulation for the popular max-critical matching polytope, i.e., the polytope of max-size critical matchings that are popular within the set of all max-size critical matchings. Thus we can efficiently solve linear optimization problems over the set of popular max-size critical matchings.