The generalized median stable matchings: finding them is not that easy

  • Authors:
  • Christine T. Cheng

  • Affiliations:
  • Department of Computer Science, University of Wisconsin-Milwaukee, Milwaukee, WI

  • Venue:
  • LATIN'08 Proceedings of the 8th Latin American conference on Theoretical informatics
  • Year:
  • 2008

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Abstract

Let I be a stable matching instance with N stable matchings. For each man m, order his N stable partners from his most preferred to his least preferred. Denote the ith woman in his sorted list as pi(m). Let αi consist of the man-woman pairs where each man m is matched to pi(m). Teo and Sethuraman proved this surprising result: for i = 1 to N, not only is αi a matching, it is also stable. The αi's are called the generalized median stable matchings of I. In this paper, we present a new characterization of these stable matchings that is solely based on I's rotation poset. We then prove the following: when i = O(log n), where n is the number of men, αi can be found efficiently; but when i is a constant fraction of N, finding αi is NP-hard. We also consider what it means to approximate the median stable matching of I, and present results for this problem.