The popular matching problem introduced by Abraham, Irving, Kavitha, and Mehlhorn is one of bipartite matching problems with one-sided preference lists. In this paper, we first propose a matroid generalization of the weighted variant of popular matchings introduced by Mestre. Then we give a characterization of weighted popular matchings in bipartite graphs with matroid constraints and one-sided preference lists containing no ties. This characterization is based on the characterization of weighted popular matchings proved by Mestre. Lastly we prove that we can decide whether a given matching is a weighted popular matching under matroid constraints in polynomial time by using our characterization.Keywords: Discrete optimization, popular matching, matroid
IntroductionThe popular matching problem introduced by Abraham, Irving, Kavitha, and Mehlhorn [1] is one of assignment problems in bipartite graphs with one-sided preference lists. Roughly speaking, a matching M is said to be popular, if there exists no other matching N such that the number of agents that prefer N to M is larger than the number of agents that prefer M to N . The concept of popularity was originally proposed by Gärdenfors [5] proposed polynomial-time algorithms for a many-to-one variant of the popular matching problem. See, e.g, [6] for the application of the popular matching problem to real-world problems.In this paper, we focus on the weighted variant of the popular matching problem introduced by Mestre [17]. In the (ordinary) popular matching problem, we consider the number of agents that prefer some matching to another matching. In other words, the opinion of every agent is valued equally. On the other hand, in this weighted variant, the opinions of agents are not valued equally. More precisely, in this setting, each agent has a weight. A matching M is said to be popular, if there exists no other matching N such that the sum of the weights of agents that prefer N to M is larger than the sum of the weights of agents that prefer M to N . Mestre [17] gave polynomial-time algorithms for the problem of deciding whether there exists a weighted popular matching, and finding a weighted popular matching if one exists. Furthermore, Sng and Manlove [21] proved that if the preference lists do not contain ties, then this problem in a many-to-one setting can be solved in polynomial time.