Improved MAX SNP-Hard Results for Finding an Edit Distance between Unordered Trees

  • Kouichi Hirata
  • Yoshiyuki Yamamoto
  • Tetsuji Kuboyama
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6661)


Zhang and Jiang (1994) have shown that the problem of finding an edit distance between unordered trees is MAX SNP-hard. In this paper, we show that this problem is MAX SNP-hard, even if (1) the height of trees is 2, (2) the degree of trees is 2, (3) the height of trees is 3 under a unit cost, and (4) the degree of trees is 2 under a unit cost.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2011

Authors and Affiliations

  • Kouichi Hirata
    • 1
  • Yoshiyuki Yamamoto
    • 2
  • Tetsuji Kuboyama
    • 3
  1. 1.Department of Artificial IntelligenceKyushu Institute of TechnologyIizukaJapan
  2. 2.Graduate School of Computer Science and Systems EngineeringKyushu Institute of TechnologyIizukaJapan
  3. 3.Computer CenterGakushuin UniversityToshimaJapan

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