An improved approximation lower bound for finding almost stable maximum matchings

  • Authors:
  • Koki Hamada;Kazuo Iwama;Shuichi Miyazaki

  • Affiliations:
  • Graduate School of Informatics, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan;Graduate School of Informatics, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan;Academic Center for Computing and Media Studies, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan

  • Venue:
  • Information Processing Letters
  • Year:
  • 2009

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Abstract

In the stable marriage problem that allows incomplete preference lists, all stable matchings for a given instance have the same size. However, if we ignore the stability, there can be larger matchings. Biro et al. defined the problem of finding a maximum cardinality matching that contains minimum number of blocking pairs. They proved that this problem is not approximable within some constant @d1 unless P=NP, even when all preference lists are of length at most 3. In this paper, we improve this constant @d to n^1^-^@e for any @e0, where n is the number of men in an input.